New onboarding (#241)

* delete old onboarding files and code

* add custom FollowButton component to Post, FeedItem, & ProfileCard

* move building suggested feed into helper lib

* show suggested posts/feed if follower list is empty

* Update tsconfig.json

* add pagination to getting new onboarding

* remove unnecessary console log

* fix naming, add better null check for combinedCursor

* In locally-combined feeds, correctly produce an undefined cursor when out of data

* Minor refactors of the suggested posts lib functions

* Show 'follow button' style of post meta in certain conditions only

* Only show follow btn in posts on the main feed and the discovery feed

* Add a welcome notice to the home feed

* Tune the timing of when the welcome banner shows or hides

* Make the follow button an observer (closes #244)

* Update postmeta to keep the follow btn after press until next render

* A couple of fixes that ensure consistent welcome screen

* Fix lint

* Rework the welcome banner

* Fix cache invalidation of follows model on user switch

* Show welcome banner while loading

* Update the home onboarding feed to get top posts from hardcode recommends

* Drop unused helper function

* Update happy path tests

---------

Co-authored-by: Paul Frazee <pfrazee@gmail.com>

src/view/com/discover/SuggestedPosts.tsx

@@ -33,7 +33,7 @@ export const SuggestedPosts = observer(() => {
         <>
           <View style={[pal.border, styles.bottomBorder]}>
             {suggestedPostsView.posts.map(item => (
-              <Post item={item} key={item._reactKey} />
+              <Post item={item} key={item._reactKey} showFollowBtn />
             ))}
           </View>
         </>