Introduce AppCompatActivity and modify account filter activities

- added PeopleThemeAppCompat for AppCompatActivity, and it will replace
  PeopleTheme eventually (same for ContactsActionBarStyleAppCompat).

- removed "icon" from styleable Mapping since there would be conflict
  when including appcompat in Android.mk.

- will clean up styles.xml after finalize all the changes.

Bug: 25629359
Change-Id: I988cee41a75800a63375e95242042ba0d0380300