[skif] Add stats tracking for surfaces/shader types

Change-Id: I74e3be5dc70e8c62e4fb979b6ccd23c3bbe4e804
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/804978
Commit-Queue: Michael Ludwig <michaelludwig@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
11 files changed