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/search/src/buffer_search.rs

@@ -46,6 +46,7 @@ use registrar::{ForDeployed, ForDismissed, SearchActionsRegistrar, WithResults};
 
 const MAX_BUFFER_SEARCH_HISTORY_SIZE: usize = 50;
 
+/// Opens the buffer search interface with the specified configuration.
 #[derive(PartialEq, Clone, Deserialize, JsonSchema, Action)]
 #[action(namespace = buffer_search)]
 #[serde(deny_unknown_fields)]
@@ -58,7 +59,17 @@ pub struct Deploy {
     pub selection_search_enabled: bool,
 }
 
-actions!(buffer_search, [DeployReplace, Dismiss, FocusEditor]);
+actions!(
+    buffer_search,
+    [
+        /// Deploys the search and replace interface.
+        DeployReplace,
+        /// Dismisses the search bar.
+        Dismiss,
+        /// Focuses back on the editor.
+        FocusEditor
+    ]
+);
 
 impl Deploy {
     pub fn find() -> Self {

crates/search/src/project_search.rs

@@ -47,7 +47,16 @@ use workspace::{
 
 actions!(
     project_search,
-    [SearchInNew, ToggleFocus, NextField, ToggleFilters]
+    [
+        /// Searches in a new project search tab.
+        SearchInNew,
+        /// Toggles focus between the search bar and the search results.
+        ToggleFocus,
+        /// Moves to the next input field.
+        NextField,
+        /// Toggles the search filters panel.
+        ToggleFilters
+    ]
 );
 
 #[derive(Default)]

crates/search/src/search.rs

@@ -23,19 +23,35 @@ pub fn init(cx: &mut App) {
 actions!(
     search,
     [
+        /// Focuses on the search input field.
         FocusSearch,
+        /// Toggles whole word matching.
         ToggleWholeWord,
+        /// Toggles case-sensitive search.
         ToggleCaseSensitive,
+        /// Toggles searching in ignored files.
         ToggleIncludeIgnored,
+        /// Toggles regular expression mode.
         ToggleRegex,
+        /// Toggles the replace interface.
         ToggleReplace,
+        /// Toggles searching within selection only.
         ToggleSelection,
+        /// Selects the next search match.
         SelectNextMatch,
+        /// Selects the previous search match.
         SelectPreviousMatch,
+        /// Selects all search matches.
         SelectAllMatches,
+        /// Cycles through search modes.
+        CycleMode,
+        /// Navigates to the next query in search history.
         NextHistoryQuery,
+        /// Navigates to the previous query in search history.
         PreviousHistoryQuery,
+        /// Replaces all matches.
         ReplaceAll,
+        /// Replaces the next match.
         ReplaceNext,
     ]
 );