Add taskbar TAPL tests

- Added TAPL objects to support TAPL tests for taskbar features
- Added tests for major taskbar features: hiding/showing the taskbar, opening all apps, lauching apps and app deep shortcuts from the taskbar/all apps page, launching apps and app deep shortcuts in splitscreen
- These tests should only run for large devices

Design: go/taskbar-tapl-tests
Test: ran tests locally with invalid configurations and remotely
Bug: 215218813
Change-Id: I3c28c339707467414aa47fa633f87fa0c1fdee57