Fix focus loop when autocompleting text on iOS

[koke]

Description

Aztec can send us selection change events after it has lost focus.

For instance the autocorrect feature will complete a partially written word when resigning focus, causing a selection change event. Forwarding this selection change could cause this RichText to regain focus and start a focus loop.

This PR prevents that selection forwarding when the RichText component isn't already selected.

I'm not sure what other side effects this could have, so pinging several people on this one 😬

Fixes: wordpress-mobile/gutenberg-mobile#1696

How has this been tested?

gutenberg-mobile PR: wordpress-mobile/gutenberg-mobile#1698

Tested with the steps in wordpress-mobile/gutenberg-mobile#1696:

1. Have a media-text block
2. Start typing some text in the paragraph until iOS suggest a completion
3. Tap on the image

Checklist:

• My code is tested.
• My code follows the WordPress code style.
• My code follows the accessibility standards.
• My code has proper inline documentation.
• I've included developer documentation if appropriate.
• I've updated all React Native files affected by any refactorings/renamings in this PR. .

[etoledom]

@koke - Should we close this? It seems to be already fixed wordpress-mobile/gutenberg-mobile#1698 (comment)

[koke]

Ah yes, thanks, I missed this one