gpui: Store action documentation (#33809)

Closes #ISSUE

Adds a new `documentation` method to actions, that is extracted from doc
comments when using the `actions!` or derive macros.

Additionally, this PR adds doc comments to as many action definitions in
Zed as possible.

Release Notes:

- N/A *or* Added/Fixed/Improved ...

crates/language_tools/src/key_context_view.rs

@@ -13,7 +13,13 @@ use ui::{
 };
 use workspace::{Item, SplitDirection, Workspace};
 
-actions!(dev, [OpenKeyContextView]);
+actions!(
+    dev,
+    [
+        /// Opens the key context view for debugging keybindings.
+        OpenKeyContextView
+    ]
+);
 
 pub fn init(cx: &mut App) {
     cx.observe_new(|workspace: &mut Workspace, _, _| {

crates/language_tools/src/lsp_log.rs

@@ -204,7 +204,13 @@ pub(crate) struct LogMenuItem {
     pub server_kind: LanguageServerKind,
 }
 
-actions!(dev, [OpenLanguageServerLogs]);
+actions!(
+    dev,
+    [
+        /// Opens the language server protocol logs viewer.
+        OpenLanguageServerLogs
+    ]
+);
 
 pub(super) struct GlobalLogStore(pub WeakEntity<LogStore>);
 

crates/language_tools/src/lsp_tool.rs

@@ -19,7 +19,13 @@ use workspace::{StatusItemView, Workspace};
 
 use crate::lsp_log::GlobalLogStore;
 
-actions!(lsp_tool, [ToggleMenu]);
+actions!(
+    lsp_tool,
+    [
+        /// Toggles the language server tool menu.
+        ToggleMenu
+    ]
+);
 
 pub struct LspTool {
     state: Entity<PickerState>,

crates/language_tools/src/syntax_tree_view.rs

@@ -15,7 +15,13 @@ use workspace::{
     item::{Item, ItemHandle},
 };
 
-actions!(dev, [OpenSyntaxTreeView]);
+actions!(
+    dev,
+    [
+        /// Opens the syntax tree view for the current file.
+        OpenSyntaxTreeView
+    ]
+);
 
 pub fn init(cx: &mut App) {
     cx.observe_new(|workspace: &mut Workspace, _, _| {