[slate-react] Pass renderEditor prop through into editor plugin

[davidchang]

Is this adding or improving a feature or fixing a bug?

Fixing a bug

What's the new behavior?

Previously, the renderEditor prop was only applied when defined on a plugin, not when it was passed as a prop to the top-level Slate Editor component. Now, the renderEditor prop will be invoked.

How does this change work?

There was just a whitelist of plugin props that gets applied to the Editor component, renderEditor needed to be on the list

Have you checked that...?

• The new code matches the existing patterns and styles.
• The tests pass with yarn test.
• The linter passes with yarn lint. (Fix errors with yarn prettier.)
• The relevant examples still work. (Run examples with yarn watch.)

Does this fix any issues or need any specific reviewers?

Fixes: #1841

[ianstormtaylor]

Good save, thanks @davidchang!