[SB][Misc] Move IconManager classes into their own files.

This should make it much easier to keep your place when looking at the
various status bar icon classes.

This also (1) cleans up a few lint warnings shown by Android Studio and
(2) Moves the icon manager classes and related classes into a new
`statusbar.phone.ui` package.

Test: status bar icons still show
Test: atest StatusBarIconControllerTest
Bug: NONE
Flag: NONE (Only moving files)
Change-Id: I4988c66922835a56e784103c9eac52e77c13fb3d