Prefilter the mergefeed to ensure a better mix of following and custom feeds (#1498)

* Prefilter the mergefeed to ensure a better mix of following and custom feeds

* Test suite improvements & tests for the mergefeed (#1499)

* Disable invite codes test for now

* Update test sim to latest iphone

* Introduce TestCtrls driver

* Add mergefeed tests

src/view/com/posts/FeedItem.tsx

@@ -299,6 +299,7 @@ export const FeedItem = observer(function FeedItemImpl({
             {item.richText?.text ? (
               <View style={styles.postTextContainer}>
                 <RichText
+                  testID="postText"
                   type="post-text"
                   richText={item.richText}
                   lineHeight={1.3}