Add package to enable selectable text on iOS

[RyanTG]

https://github.com/bluesky-social/react-native-uitextview

Worked fine at the moment aside from not being able to center text. But that's a dealbreaker, so will wait to see if that issue get resolved.

[RyanTG]

That package does support centering now.

It works. Though on the Event details modal, we are already splitting apart the text in order to detect urls, and I can't get that functionality plus the selectable text to work together. I would rather not have inconsistent behavior.

[RyanTG]

Closing for now. I'm also not super comfortable using a package that maps every string in text.