In addition to looking nicer, this fixes two accessibility issues ("no hint when text is entered" and "reason for disabled button is unclear").
This requires a bit of theme merging black magic, because TextInputLayout requires a Theme.AppCompat descendant, which the Settings theme isn't.
Fixes: 356398157
Fixes: 370654542
Fixes: 369942776
Test: atest ZenModeEditNamePreferenceControllerTest
Flag: android.app.modes_ui
Change-Id: I92d8ec044dabc6daed5d755e206120ec7abc143e
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