Add a C-api for retrieving display info.

As HWUI will need to depend on ABI-stable interfaces moving forward, we
need such an interface against SurfaceComposer for retrieving display
metadata.

This CL won't contain a map file to stabilize the ABI yet, as I expect
that there will be some flux due to refresh rate apis.

Bug: 136263392
Test: builds
Change-Id: I7227e2e72789d36a21534840eac88817135251c3