Add `google-pubsub-grpc()` destination #1115

Job	Run time
create-source-tarball	2m 57s
create-packages / almalinux-8	3m 59s
create-packages / almalinux-9	7m 53s
create-packages / debian-bookworm	6m 42s
create-packages / debian-testing	6m 13s
create-packages / fedora-41	8m 0s
create-packages / ubuntu-noble	9m 43s
	45m 27s

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