FR(snippetgen): Add support for REST snippets

[parthea]

REST snippets are currently being excluded. This issue tracks adding support for REST snippets. See the TODO comment below.

gapic-generator-python/gapic/generator/generator.py

Lines 156 to 160 in 119a3f1

	# TODO: Support the generation of REST snippets.
	autogen_specs = [
	spec for spec in autogen_specs
	if spec["transport"] != api.TRANSPORT_REST
	]