* Put themed reader context in adapter
This avoids creating themed context everytime the page holder is created, this
also allows the transition view to use the same themed context.
* Check against app night mode to create themed reader context
* ReaderTransitionView: Use context theme color for texts
The whole reader will need to be recreated when changing reader background while
webtoon mode is used, because recreating just the RecyclerView without messing
up the scroll position is impossible (I hope I just missed something).
* Fix ReaderActivity system bars behavior
* Fix ReaderActivity transition view text color
* Don't change reader navbar color when windowLightNavigationBar is not available
