Hide gemini task when invoked in Desktop Task

- When gemini or similar transparent tasks are invoked in Desktop, currently they look cropped in existing desktop tile in overview.
- This happens when top activity is transparent as well as activity stack below are also transparent.
- Currently they are not part of desktop tasks list, since they are considered as "non active" tasks.
- We first add such tasks when in Desktop task list.
- Then we hide it in overview as well as on Taskbar.

Bug: 390180598
Test: DesktopTaskViewModelTest, RecentTasksControllerTest,
TaskbarRecentAppsControllerTest
Flag: EXEMPT bugfix

Change-Id: If6714c06bdd6340befa7d76c5de83f9691a498eb