Make gapic.bzl rules compliant with the standalone microgenerator spec (#2743)
Make gapic.bzl rules compliant with the standalone microgenerator spec (#2743)

Make gapic.bzl rules (specifically gapic_srcjar rule) standalone microgenerator spec-compliant (support --descriptor, --package and --output parameters).


googleapis/gapic-generator,googleapis/gapic-generator,googleapis/gapic-generator,googleapis/gapic-generator,googleapis/gapic-generator,googleapis/gapic-generator,googleapis/gapic-generator