Settings: PreviewPagerAdapter: copy the full theme

getThemeResId() returns the theme resource id which is defined inside AndroidManifest.xml.
If you set a theme via code (or add extra attributes using applyStyle method), the new theme will not be carried over.
Fix this by using setTo method with the context theme as argument.

Issue: https://issuetracker.google.com/37543358

Test: set new theme via code (or add extra attributes using applyStyle method) and check if they are carried over to the configContext context

Change-Id: I82739fe47b2d5b2d05da4cb3759b630b10dc8c8f