Rename CPU tessellation to "triangulation"

Ambiguity has come up re: what "tessellation" means in Ganesh. I
believe that, in the context of a graphics library, "tessellation"
should refer to the hardware pipeline feature of submitting patches
and tessellating them on the GPU. This CL therefore renames classes
that triangulate things on the CPU to call it "triangulation".

Change-Id: Ic8515ea6a33000f1b638a852d5122bc9bd6b38f2
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/279236
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Chris Dalton <csmartdalton@google.com>
17 files changed