graphics: Add display color sampling interface.

Add a graphics.composer@2.3 interface that will expose
color sampling hardware present on some devices to the
framework. Adds:
  getDisplayedContentSamplingAttributes
  setDisplayedContentSamplingEnabled
  getDisplayedContentSample

Test: boot up pixel3
Test: VtsHalGraphicsComposerV2_3TargetTest on revved Pixel3 hwcomposer
Bug: 116028976
Change-Id: I88455f200590926f677c47efc39e9b6678e2318c