Rename Runtime Effect-compatible ES2 error tests to .rts.

This is useful because it will allow these tests to be supported in
Android CTS, where only Runtime Effects are API-accessible.

This CL updates the C++ test harness so that .rts files in the error/
directory are found, and tweaks error tests as necessary to make them
Runtime Effect-compatible. For instance, Runtime Effects enforce the
parameters on main(), which adds extra errors that we don't want. And
some error tests require ES3 (e.g. array constructors) and so those
tests remain as .sksl files.

In this CL, only tests beginning with A are updated. The remaining tests
will be updated in followup CLs.

Bug: skia:13042
Auto-Submit: John Stiles <johnstiles@google.com>
Reviewed-by: Ethan Nicholas <ethannicholas@google.com>
Change-Id: Iddba1ea7b51e8928268743ed4b73a1a173759e4f
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/524096
Reviewed-by: Derek Sollenberger <djsollen@google.com>
Commit-Queue: John Stiles <johnstiles@google.com>
26 files changed