[flexiglass] BouncerViewModel is now SysUiViewModel

Also converts the following child view-models:
- BouncerMessageViewModel
- PinBoncerViewModel
- PatternBouncerViewModel
- PasswordBouncerViewModel

For more info, please see go/sysui-arch:summer-24

Bug: 354270224
Flag: com.android.systemui.scene_container
Test: all existing unit tests currently working
Test: manually verified each authentication method including correct
auth, wrong auth, timeout, and correct auth after wrong auth and after
timeour

Change-Id: Id0cdf01bcdd2a17a1ff92f416c8f489a9876dcd4