Adding support for portrait orientation in tutorial selection screen

Extracting three tutorial buttons to separate composable and making its parent depend on the orientation.
If we're in landscape they are positioned horizontally and otherwise vertically.
Note this change still doesn't remove enforcing landscape orientation from AndroidManifest so for now it's still letterboxed in portrait.

Also drive-by fix for inset paddings.

Fixes: 369829466
Bug: 376020472
Test: screenshots
Flag: com.android.systemui.shared.new_touchpad_gestures_tutorial
Change-Id: Ie5417409f896703dd5d60d0357f256701f5f5de4