Resolve NPE when mini resolver is rotated

Was attempting to adjust padding on a View that didn't exist.

Also adding additional conditional behavior for similar issues:
- Fix the padding at the bottom based upon insets.
- Only trigger mini resolver for ResolverActivity itself.
- Add comments defining mini resolver.

Test: atest ResolverActivityTest
Test: Manual test of rotation not crashing and padding looking better.
Bug: 222497968
Bug: 175433480
Change-Id: Ie38787f61dc523bd812b828ec16830b91f61ce0b