Also fixed paddings a bit (e.g. Done button was too close to the icon grid).
Fixes: 369503296
Test: manual
Flag: android.app.modes_ui
Change-Id: Ic7b7dc9584db1f04b448fce828a8ec70cf17f06a
This also unifies the "icon picker" screen with the new "add mode" screen since in both cases we want to edit name and icon together (and not save updates until the user confirms).
Bug: 326442408
Bug: 346278854
Test: atest com.android.settings.notification.modes
Flag: android.app.modes_ui
Change-Id: I8a9d07ba0b6c55f3abc1b9884f278d51d178dc83