SF: Add dumpsys flags to dump displays

Dump display configuration (--displays) and composition state (--comp-
displays) separately.

Use consistent formatting. Remove noise, e.g. repetitive display modes,
physical display state that is expectedly missing for virtual displays.

Bug: 182939859
Test: dumpsys SurfaceFlinger --displays
Test: dumpsys SurfaceFlinger --comp-displays
Change-Id: I787eedb82d76c74363e653a648ae88699096cc47