RichText: split out inline warning

[ellatrix]

Description

This is part of an effort to split RichText into smaller pieces and rewrite it with hooks. This component can later be converted to a hook.

How has this been tested?

Change a rich text element's display property to inline and you should see the warning.

Screenshots

Types of changes

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. .