Address `RestrictedApi` lint warning in `WPMainNavigationView`

[wzieba]

Expected behavior

WPMainNavigationView doesn't use internal-only classes from Material library.

Actual behavior

WPMainNavigationView uses BottomNavigationMenuView and BottomNavigationItemView classes, which are restricted to library group only (internal in a sense).

https://github.com/material-components/material-components-android/blob/e1a103e2e11984baa675b06d9b52290f88f4478e/lib/java/com/google/android/material/bottomnavigation/BottomNavigationMenuView.java#L40-L42

Steps to reproduce the behavior

Remove lint rule suppression in WPMainNavigationView and run lintWordpressVanillaRelease task

[dangermattic]

Thanks for reporting! 👍