exec.go: Provide functions to access tag criteria.

- Add two new functions, `testplan.get_tag_criteria()` and
`testplan.get_suite_name()`. In future CLs, a map from
Starlark file -> [TemplateParameters] will be read from
the command line. Currently these two functions will always
return errors because this command line flag isn't added yet.

- It is possible multiple tag criteria are provided for a given
Starlark file (the flag will read a list of tag criteria for each
file). Thus, provide a function to access suite name so Starlark
files can prevent collisions in test suite names. Callers of
`ExecTestPlan` (e.g. `Generate`) should validate that test
suite names don't collide when a file is called multiple times
with different tag criteria.

BUG=b:278886899
TEST=CQ

Change-Id: I42f0f34d60d6de7c9215a15c34e4ce6361a520bb
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/dev-util/+/4519112
Tested-by: Andrew Lamb <andrewlamb@chromium.org>
Reviewed-by: Navil Perez <navil@google.com>
Commit-Queue: Andrew Lamb <andrewlamb@chromium.org>
3 files changed