Add key contexts for Pickers (#35665)

Closes: https://github.com/zed-industries/zed/issues/35430

Added:
- Workspace > CommandPalette
- Workspace > GitBranchSelector
- Workspace > GitRepositorySelector
- Workspace > RecentProjects
- Workspace > LanguageSelector
- Workspace > IconThemeSelector
- Workspace > ThemeSelector

Release Notes:

- Added new keymap contexts for various Pickers - CommandPalette,
GitBranchSelector, GitRepositorySelector, RecentProjects,
LanguageSelector, IconThemeSelector, ThemeSelector

crates/recent_projects/src/recent_projects.rs

@@ -141,6 +141,7 @@ impl Focusable for RecentProjects {
 impl Render for RecentProjects {
     fn render(&mut self, _: &mut Window, cx: &mut Context<Self>) -> impl IntoElement {
         v_flex()
+            .key_context("RecentProjects")
             .w(rems(self.rem_width))
             .child(self.picker.clone())
             .on_mouse_down_out(cx.listener(|this, _, window, cx| {