Improve draft logic and enable draft resume on startup

[hjiangsu]

Pull Request Description

This PR improves on the existing draft logic and enables drafts to be resumed at startup when Thunder is killed. Additionally, some of the draft logic was re-worked and consolidated:

• Added a startup method which automatically opens the create post/comment page if a draft was in-progress when Thunder is killed
• Added additional fields to Draft table (active, accountId, nsfw, languageId). The active field indicates the draft that is currently being edited and is used to restore the draft on startup
• Added DraftRepository to move and consolidate database-related logic

For the create post/comment pages, the old draft timer logic was also replaced with a debounce logic. Additionally, Thunder should now save the draft state when the AppLifecycleState changes (e.g., when Thunder is backgrounded). These two changes should help reduce cases of lost in-progress work.

Issue Being Fixed

Issue Number: #2050

Screenshots / Recordings

Checklist

• If a new package was added, did you ensure it uses an appropriate license and is actively maintained?
• Did you use localized strings (and added appropriate descriptions) where applicable?
• Did you add semanticLabels where applicable for accessibility?