Lazily create OverlaySheets

Summary:
In the timeline, OverlaySheets take extra long time to load, because it does a lot of setup work. This commit wrap them in Components and create the items only when the corresponding actions are triggered.

Type: fix

Test Plan: Verify that unit tests pass. Check all popups in the timeline still work.

Reviewers: O1 the Kazv Project, nannanko

Reviewed By: O1 the Kazv Project, nannanko

Differential Revision: https://iron.lily-is.land/D42