[Bottomsheet] draw under navbar

[hrach]

This PR fixes:

• lib: drawing bottomsheet content under navbar;
• catalog: reseting layout height in catalog demo app;
• catalog: dynamic setting of light navbar for bottomsheet; if it would be done declaratively, it's ok.

Note: the demo uses statically defined 400px peek height, which is not much convenient.

Preview

[hrach]

A workaround we currently use in our BottomSheetDialogFragments:

    override fun onActivityCreated(savedInstanceState: Bundle?) {
        super.onActivityCreated(savedInstanceState)
        dialog?.findViewById<View>(R.id.container)?.fitsSystemWindows = false
        dialog?.findViewById<View>(R.id.design_bottom_sheet)?.fitsSystemWindows = true
    }

[melaniegoetz]

Hey there, thanks for contributing with this PR! 🎉
We already have a similar fix in the works (that will encompass parts 1 & 2 of these changes). That will released to github soon, and once it is, then we can accept a PR for part 3 (catalog: dynamic setting of light navbar for bottomsheet; if it would be done declaratively, it's ok). Thank you!

[hrach]

Hi guys, any progress?