PanelExpansionStateManager: add new parameter for raw drag amount

This will be needed for split-shade expansion motion. The absolute value of the expansion will be used instead of fractions.

+ refactor multiple primitive parameters into a single high-level type parameter.

Test: unit tests
Change-Id: Ia35f79ff42f29e44e4123776be30ebc33ee2aab0
Merged-In: Ia35f79ff42f29e44e4123776be30ebc33ee2aab0