Intercept clicks for non-supported split targets on workspace

* If we're in split selection state we disable the following
- G icon on PSB
- Lens icon on PSB
- Smartspace
- Widgets

Bug: 295467097
Test: Enter split contextual and observe split instructions
view going boing when tapping on unsupported target
Flag: com.android.wm.shell.enable_split_contextual

Change-Id: Ia7783472f3de9359c2784788be5f35596cbc8deb