[Quote] Tapping return at end of block doesn't create new block

Note: I'm running a custom version of WPiOS, built off of develop (iOS 12.4, iPhone Xs Max). I haven't tried a build w/ Quote on Android yet.

## Steps to reproduce

* Select a Quote block with some text
* Go to end of block's contents
* Tap enter

## Expected Behavior

I expect a new block to be created, just like happens on other RichText blocks.