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>

__tests__/state/models/onboard.test.ts

@@ -1,46 +0,0 @@
-import {
-  OnboardModel,
-  OnboardStageOrder,
-} from '../../../src/state/models/onboard'
-
-describe('OnboardModel', () => {
-  let onboardModel: OnboardModel
-
-  beforeEach(() => {
-    onboardModel = new OnboardModel()
-  })
-
-  afterAll(() => {
-    jest.clearAllMocks()
-  })
-
-  it('should start/stop correctly', () => {
-    onboardModel.start()
-    expect(onboardModel.isOnboarding).toBe(true)
-    onboardModel.stop()
-    expect(onboardModel.isOnboarding).toBe(false)
-  })
-
-  it('should call the next method until it has no more stages', () => {
-    onboardModel.start()
-    onboardModel.next()
-    expect(onboardModel.stage).toBe(OnboardStageOrder[1])
-
-    onboardModel.next()
-    expect(onboardModel.isOnboarding).toBe(false)
-    expect(onboardModel.stage).toBe(OnboardStageOrder[0])
-  })
-
-  it('serialize and hydrate', () => {
-    const serialized = onboardModel.serialize()
-    const newModel = new OnboardModel()
-    newModel.hydrate(serialized)
-    expect(newModel).toEqual(onboardModel)
-
-    onboardModel.start()
-    onboardModel.next()
-    const serialized2 = onboardModel.serialize()
-    newModel.hydrate(serialized2)
-    expect(newModel).toEqual(onboardModel)
-  })
-})