Optimize screen decor insets calculation

This stores the computed decor insets and frame excluding insets.
So it can save 99% time of recomputing the insets every time during
starting an activity. E.g. dozen times of "prepare display info/frame,
compute window layout of insets source windows, calculate insets"
becomes "get result from array".

The saved decor insets will be updated when:
- Display metrics is changed (DC#updateBaseDisplayMetrics).
- Insets provider is added/removed/changed.

Also
- Use DisplayCutout rather than WmDisplayCutout to simplify
  passing the cutout between methods.
- Optimize getSourceProvider to avoid unnecessary object allocation.

This also fixes an issue that the display doesn't compute the latest
configuration when navigation mode is changed. Now it is fixed by
checking if the insets provider has layout changes and then recompute
screen configuration.

Bug: 238399969
Bug: 159103089
Test: atest DisplayPolicyInsetsTests DisplayPolicyLayoutTests
      DisplayPolicyTests#testUpdateDisplayConfigurationByDecor
Test: Change navigation mode or display size (density) in Settings.
      And then swipe-up or press home key, there won't be a
      frozen effect (display configuration change).

Change-Id: If6c28a89939372e6362b92f469ef7d793e8ec215