fix: appbar content title container adjustments

[lukewalczak]

Summary

PR introduces adjustments for handling the title prop in Appbar.Content to wrap only the title string within the default Text component. Other types passed into title are rendered directly in the View container.

Related issue

• Appbar.Header.title renders custom components high on Android #3572

Test plan

Added unit tests.

[github-actions]

The mobile version of example app from this branch is ready! You can see it here.

[krozniata]

LGTM!
It would be nice to add example to Usage using component as a title (maybe the one from tests)

[gedu]

if title is a string using the titleStyle doesn't make sense, what do you think to split the type into something like:

type TitleString = {
  /**
   * Text for the title.
   */
  title: string;
  titleStyle?:  StyleProp<TextStyle>;
};

type TitleElement = {
  /**
   * Element for the title.
   */
  title: React.ReactElement;
  /**
   * Style for the title.
   */
  titleStyle?: never;
};

// remove title and titleStyle from Props
export type Props = $RemoveChildren<typeof View> & { ... } & (TitleElement | TitleString);

So if you try to add title as string and titleStyle, TS warns you.

[callstack-bot]

Hey @lukewalczak, thank you for your pull request 🤗. The documentation from this branch can be viewed here.