* Subscribe to user posts and comments independently
* Track when comments and posts subscriptions are set to filter out old items
* Only send push notification to subscribed user if posts/comments enabled
* Remove `posts` and `comments` boolean fields on UserSub, rely solely on timestamps
* First pass of user subscriptions
* add new db model to track subscriptions
* update user typedef and api resolver for subscription state
* add subscribe action to user profile page
* add mutation to subscribe to a user
* Update notifications queries, hasNewNotes queries for FollowActivity note type
* Only show items that have been created since subscribing to the user
* Send push notifications to user subscribers for posts and comments
* Rename item dropdown to action dropdown and re-use for item info and user actions
* Don't allow self-follows
* Add index on followee for faster lookups
* Don't show subscribe action if not logged in
* small style enhance
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Co-authored-by: Keyan <34140557+huumn@users.noreply.github.com>
Co-authored-by: keyan <keyan.kousha+huumn@gmail.com>