New navigation model (#1)

* Flatten all routing into a single stack

* Replace router with custom implementation

* Add shell header and titles

* Add tab selector

* Add back/forward history menus on longpress

* Fix: don't modify state during render

* Add refresh() to navigation and reroute navigations to the current location to refresh instead of add to history

* Cache screens during navigation to maintain scroll position and improve load-time for renders

src/view/com/notifications/Feed.tsx

@@ -1,7 +1,6 @@
 import React from 'react'
 import {observer} from 'mobx-react-lite'
 import {Text, View, FlatList} from 'react-native'
-import {OnNavigateContent} from '../../routes/types'
 import {
   NotificationsViewModel,
   NotificationsViewItemModel,
@@ -10,17 +9,15 @@ import {FeedItem} from './FeedItem'
 
 export const Feed = observer(function Feed({
   view,
-  onNavigateContent,
 }: {
   view: NotificationsViewModel
-  onNavigateContent: OnNavigateContent
 }) {
   // TODO optimize renderItem or FeedItem, we're getting this notice from RN: -prf
   //   VirtualizedList: You have a large list that is slow to update - make sure your
   //   renderItem function renders components that follow React performance best practices
   //   like PureComponent, shouldComponentUpdate, etc
   const renderItem = ({item}: {item: NotificationsViewItemModel}) => (
-    <FeedItem item={item} onNavigateContent={onNavigateContent} />
+    <FeedItem item={item} />
   )
   const onRefresh = () => {
     view.refresh().catch(err => console.error('Failed to refresh', err))