Add separate OWNERS file for SF tests.

Currently a lot of the SurfaceFlinger tests owned by WM automatically go to
the first person listed in the parent OWNERS file from CoGS. Extracting
tests with clear ownerships in this OWNERS file to reduce triage overhead.

Bug: 334170221
Test: N/A
Change-Id: I9728f07d4411bd9a55984992e0b520624c6be90c