What?

PR introduces a new global state for selectedNote, along with an associated private action and selector. This is similar to the selectBlock action.

Why?

The local state served us well initially, but it had limitations and blocked integration with other features, such as the Command Palette, Keyboard Shortcuts and RichText formats. It also required a lot of prop drilling.

Most of the code is extracted from my local inline notes format branch.

Todo(s)

• Add action flag to move focus to the selected note.

Testing Instructions

• CI checks are passing. We've good e2e tests coverage for the feature.
• Smoke test the floating note, confirm it works as before.

Testing note focus via action

• Apply the patch from below and try adding a new note or selection exiting via the block toolbar. Focus should move as before.

diff --git a/packages/editor/src/components/collab-sidebar/index.js b/packages/editor/src/components/collab-sidebar/index.js
index 296e491a296..de830bca2e7 100644
--- a/packages/editor/src/components/collab-sidebar/index.js
+++ b/packages/editor/src/components/collab-sidebar/index.js
@@ -150,13 +150,7 @@ function NotesSidebar( { postId } ) {
 			return;
 		}
 
-		selectNote( currentThread ? currentThread.id : 'new' );
-		focusCommentThread(
-			currentThread?.id,
-			commentSidebarRef.current,
-			// Focus the textarea when creating a new note.
-			! currentThread ? 'textarea' : undefined
-		);
+		selectNote( currentThread ? currentThread.id : 'new', { focus: true } );
 		toggleBlockSpotlight( clientId, true );
 	}