Search Contributions Cleanup (microsoft#165538)

Major cleanup on search contribs/actions, namely:
- converting all `Action` and related registrations to `Action2`
- Converting the `Actionbar` that appears on hover of a search result to `MenuWorkbenchToolBar`
- Overall organization
- Converting any `ICommandHandler` to functions if they don't need to be `ICommandHandler`
- Adding titles to all search commands

Author: andreamah

src/vs/platform/actions/common/actions.ts

@@ -103,6 +103,7 @@ export class MenuId {
 	static readonly SCMSourceControl = new MenuId('SCMSourceControl');
 	static readonly SCMTitle = new MenuId('SCMTitle');
 	static readonly SearchContext = new MenuId('SearchContext');
+	static readonly SearchActionMenu = new MenuId('SearchActionContext');
 	static readonly StatusBarWindowIndicatorMenu = new MenuId('StatusBarWindowIndicatorMenu');
 	static readonly StatusBarRemoteIndicatorMenu = new MenuId('StatusBarRemoteIndicatorMenu');
 	static readonly StickyScrollContext = new MenuId('StickyScrollContext');