Change color of border around BrightnessSlider

Allow providing a color for idle and another for mirroring and animate
between the two.

Also, force the slider in QSFragmentCompose to always be in dark mode.

Test: manual, in fragment and dual shade
Fixes: 394923812
Flag: com.android.systemui.qs_ui_refactor_compose_fragment
Flag: com.android.systemui.scene_container

Change-Id: I24c29d20244cffb4b2f785599fab3c9cc4ab65f0