Show a dialog if bluetooth key is missing when reconnecting

Previous change is reverted due to test failure in b/362901443.

BUG: 360031750
Test: atest BluetoothKeyMissingDialogTest
Flag: com.android.settings.flags.enable_bluetooth_key_missing_dialog
Change-Id: I05b940e8aac26c14f93baa19c224ad98c291b891