keymap_ui: Add open keymap JSON button (#36182)

Closes #ISSUE

Release Notes:

- Keymap Editor: Added a button in the top left to allow opening the
keymap JSON file. Right clicking the button provides shortcuts to
opening the default Zed and Vim keymaps as well.

crates/icons/src/icons.rs

@@ -140,6 +140,7 @@ pub enum IconName {
     Image,
     Indicator,
     Info,
+    Json,
     Keyboard,
     Library,
     LineHeight,

crates/settings_ui/Cargo.toml

@@ -42,8 +42,10 @@ tree-sitter-rust.workspace = true
 ui.workspace = true
 ui_input.workspace = true
 util.workspace = true
+vim.workspace = true
 workspace-hack.workspace = true
 workspace.workspace = true
+zed_actions.workspace = true
 
 [dev-dependencies]
 db = {"workspace"= true, "features" = ["test-support"]}

crates/settings_ui/src/keybindings.rs

@@ -23,7 +23,7 @@ use settings::{BaseKeymap, KeybindSource, KeymapFile, Settings as _, SettingsAss
 use ui::{
     ActiveTheme as _, App, Banner, BorrowAppContext, ContextMenu, IconButtonShape, Indicator,
     Modal, ModalFooter, ModalHeader, ParentElement as _, Render, Section, SharedString,
-    Styled as _, Tooltip, Window, prelude::*,
+    Styled as _, Tooltip, Window, prelude::*, right_click_menu,
 };
 use ui_input::SingleLineInput;
 use util::ResultExt;
@@ -1536,6 +1536,33 @@ impl Render for KeymapEditor {
                     .child(
                         h_flex()
                             .gap_2()
+                            .child(
+                                right_click_menu("open-keymap-menu")
+                                    .menu(|window, cx| {
+                                        ContextMenu::build(window, cx, |menu, _, _| {
+                                            menu.header("Open Keymap JSON")
+                                                .action("User", zed_actions::OpenKeymap.boxed_clone())
+                                                .action("Zed Default", zed_actions::OpenDefaultKeymap.boxed_clone())
+                                                .action("Vim Default", vim::OpenDefaultKeymap.boxed_clone())
+                                        })
+                                    })
+                                    .anchor(gpui::Corner::TopLeft)
+                                    .trigger(|open, _, _|
+                                        IconButton::new(
+                                            "OpenKeymapJsonButton",
+                                            IconName::Json
+                                        )
+                                        .shape(ui::IconButtonShape::Square)
+                                        .when(!open, |this|
+                                            this.tooltip(move |window, cx| {
+                                                Tooltip::with_meta("Open Keymap JSON", Some(&zed_actions::OpenKeymap),"Right click to view more options", window, cx)
+                                            })
+                                        )
+                                        .on_click(|_, window, cx| {
+                                            window.dispatch_action(zed_actions::OpenKeymap.boxed_clone(), cx);
+                                        })
+                                    )
+                            )
                             .child(
                                 div()
                                     .key_context({