Allow LauncherState to define floating search side margins.

This lets home screen align to workspace icons while All Apps
aligns with those icons. In addition, on tablets where the QSB
is inlined with the hotseat, floating search bar can also move
horizontally accordingly.

Bug: 275635606
Bug: 259619990
Test: Manual on tablet as well as foldable.
Flag: ENABLE_FLOATING_SEARCH_BAR

Change-Id: I67745c66390736cdf39d969ef7767096ae13c671