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/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>);