[skif] Update MatrixConvolution to use FilterResult Change-Id: Ia6480a61a84eccaa6987498278fe1daa5527dd80 Reviewed-on: https://skia-review.googlesource.com/c/skia/+/724960 Reviewed-by: Robert Phillips <robertphillips@google.com> Reviewed-by: Brian Osman <brianosman@google.com> Commit-Queue: Michael Ludwig <michaelludwig@google.com>