ui crate docs & spring cleaning (#18768)

Similar to https://github.com/zed-industries/zed/pull/18690 &
https://github.com/zed-industries/zed/pull/18695, this PR enables
required docs for `ui` and does some cleanup.

Changes:
- Enables the `deny(missing_docs)` crate-wide.
- Adds `allow(missing_docs)` on many modules until folks pick them up to
document them
- Documents some modules (all in `ui/src/styles`)
- Crate root-level organization: Traits move to `traits`, other misc
organization
- Cleaned out a bunch of unused code.

Note: I'd like to remove `utils/format_distance` but the assistant panel
uses it. To move it over to use the `time_format` crate we may need to
update it to use `time` instead of `chrono`. Needs more investigation.

Release Notes:

- N/A

crates/ui/src/components/keybinding.rs

@@ -1,5 +1,7 @@
+#![allow(missing_docs)]
+use crate::PlatformStyle;
 use crate::{h_flex, prelude::*, Icon, IconName, IconSize};
-use gpui::{relative, Action, FocusHandle, IntoElement, Keystroke};
+use gpui::{relative, Action, FocusHandle, IntoElement, Keystroke, WindowContext};
 
 #[derive(IntoElement, Clone)]
 pub struct KeyBinding {
@@ -192,3 +194,173 @@ impl KeyIcon {
         Self { icon }
     }
 }
+
+/// Returns a textual representation of the key binding for the given [`Action`].
+pub fn text_for_action(action: &dyn Action, cx: &mut WindowContext) -> Option<String> {
+    let key_binding = cx.bindings_for_action(action).last().cloned()?;
+    Some(text_for_key_binding(key_binding, PlatformStyle::platform()))
+}
+
+/// Returns a textual representation of the key binding for the given [`Action`]
+/// as if the provided [`FocusHandle`] was focused.
+pub fn text_for_action_in(
+    action: &dyn Action,
+    focus: &FocusHandle,
+    cx: &mut WindowContext,
+) -> Option<String> {
+    let key_binding = cx.bindings_for_action_in(action, focus).last().cloned()?;
+    Some(text_for_key_binding(key_binding, PlatformStyle::platform()))
+}
+
+/// Returns a textual representation of the given key binding for the specified platform.
+pub fn text_for_key_binding(
+    key_binding: gpui::KeyBinding,
+    platform_style: PlatformStyle,
+) -> String {
+    key_binding
+        .keystrokes()
+        .iter()
+        .map(|keystroke| text_for_keystroke(keystroke, platform_style))
+        .collect::<Vec<_>>()
+        .join(" ")
+}
+
+/// Returns a textual representation of the given [`Keystroke`].
+pub fn text_for_keystroke(keystroke: &Keystroke, platform_style: PlatformStyle) -> String {
+    let mut text = String::new();
+
+    let delimiter = match platform_style {
+        PlatformStyle::Mac => '-',
+        PlatformStyle::Linux | PlatformStyle::Windows => '+',
+    };
+
+    if keystroke.modifiers.function {
+        match platform_style {
+            PlatformStyle::Mac => text.push_str("fn"),
+            PlatformStyle::Linux | PlatformStyle::Windows => text.push_str("Fn"),
+        }
+
+        text.push(delimiter);
+    }
+
+    if keystroke.modifiers.control {
+        match platform_style {
+            PlatformStyle::Mac => text.push_str("Control"),
+            PlatformStyle::Linux | PlatformStyle::Windows => text.push_str("Ctrl"),
+        }
+
+        text.push(delimiter);
+    }
+
+    if keystroke.modifiers.alt {
+        match platform_style {
+            PlatformStyle::Mac => text.push_str("Option"),
+            PlatformStyle::Linux | PlatformStyle::Windows => text.push_str("Alt"),
+        }
+
+        text.push(delimiter);
+    }
+
+    if keystroke.modifiers.platform {
+        match platform_style {
+            PlatformStyle::Mac => text.push_str("Command"),
+            PlatformStyle::Linux => text.push_str("Super"),
+            PlatformStyle::Windows => text.push_str("Win"),
+        }
+
+        text.push(delimiter);
+    }
+
+    if keystroke.modifiers.shift {
+        match platform_style {
+            PlatformStyle::Mac | PlatformStyle::Linux | PlatformStyle::Windows => {
+                text.push_str("Shift")
+            }
+        }
+
+        text.push(delimiter);
+    }
+
+    fn capitalize(str: &str) -> String {
+        let mut chars = str.chars();
+        match chars.next() {
+            None => String::new(),
+            Some(first_char) => first_char.to_uppercase().collect::<String>() + chars.as_str(),
+        }
+    }
+
+    let key = match keystroke.key.as_str() {
+        "pageup" => "PageUp",
+        "pagedown" => "PageDown",
+        key => &capitalize(key),
+    };
+
+    text.push_str(key);
+
+    text
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_text_for_keystroke() {
+        assert_eq!(
+            text_for_keystroke(&Keystroke::parse("cmd-c").unwrap(), PlatformStyle::Mac),
+            "Command-C".to_string()
+        );
+        assert_eq!(
+            text_for_keystroke(&Keystroke::parse("cmd-c").unwrap(), PlatformStyle::Linux),
+            "Super+C".to_string()
+        );
+        assert_eq!(
+            text_for_keystroke(&Keystroke::parse("cmd-c").unwrap(), PlatformStyle::Windows),
+            "Win+C".to_string()
+        );
+
+        assert_eq!(
+            text_for_keystroke(
+                &Keystroke::parse("ctrl-alt-delete").unwrap(),
+                PlatformStyle::Mac
+            ),
+            "Control-Option-Delete".to_string()
+        );
+        assert_eq!(
+            text_for_keystroke(
+                &Keystroke::parse("ctrl-alt-delete").unwrap(),
+                PlatformStyle::Linux
+            ),
+            "Ctrl+Alt+Delete".to_string()
+        );
+        assert_eq!(
+            text_for_keystroke(
+                &Keystroke::parse("ctrl-alt-delete").unwrap(),
+                PlatformStyle::Windows
+            ),
+            "Ctrl+Alt+Delete".to_string()
+        );
+
+        assert_eq!(
+            text_for_keystroke(
+                &Keystroke::parse("shift-pageup").unwrap(),
+                PlatformStyle::Mac
+            ),
+            "Shift-PageUp".to_string()
+        );
+        assert_eq!(
+            text_for_keystroke(
+                &Keystroke::parse("shift-pageup").unwrap(),
+                PlatformStyle::Linux
+            ),
+            "Shift+PageUp".to_string()
+        );
+        assert_eq!(
+            text_for_keystroke(
+                &Keystroke::parse("shift-pageup").unwrap(),
+                PlatformStyle::Windows
+            ),
+            "Shift+PageUp".to_string()
+        );
+    }
+}