Restructure SkSLTest to use test flags instead of multiple macros.
Restructure SkSLTest to use test flags instead of multiple macros.

At this CL, we should run exactly the same tests as before; the only
difference is that we enable and disable tests via SkSLTestFlags instead
of using different SKSL_TEST_xxxxxx macros for different test types.

There is an inert flag for SkQP; this will be implemented in a followup
CL.

The SKSL_TEST block now extends past 100 characters in some spots
because it was, overall, a lot easier to read and edit tabular data in
a tabular format than with inconsistent formatting and line wrapping.

Change-Id: Ic90f88b10c6e59357275b471e6e86e53e611f101
Bug: skia:13037
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/518138
Auto-Submit: John Stiles <f4fcf42d3bb5924557f1eeb3be66747535e585da@google.com>
Reviewed-by: Arman Uguray <b18dd57f0c81bc1fc439e303e71d2866b09f3bd2@google.com>
Commit-Queue: John Stiles <f4fcf42d3bb5924557f1eeb3be66747535e585da@google.com>

google/skia,google/skia,google/skia,google/skia,google/skia,google/skia,google/skia,google/skia,google/skia,google/skia