SettingsLib synced by Copybara

CollapsingToolbarBaseActivity
 - Add CollapsingToolbarAppCompatActivity to support AppCompatActivity
 - Adjust minSDK back to 21
MainSwitchPreference
 - support iconSpaceReserved before S

Test: manual & robotest
Change-Id: I184764c476cb0142a7f8c967fb09588d8ff6879d
15 files changed