improvement: implement a subscription notification batcher #1188

Job	Run time
ash-ci / mix deps.get	14s
ash-ci / MIX_ENV=test mix.compile	40s
ash-ci / MIX_ENV=dev mix.compile	25s
ash-ci / audit	1m 0s
ash-ci / mix docs	43s
ash-ci / mix spark.cheat_sheets --check	34s
ash-ci / mix spark.formatter --check	34s
ash-ci / mix sobelow	35s
ash-ci / mix format --check-formatted	44s
ash-ci / mix credo --strict	39s
ash-ci / mix ash.codegen --check	0s
ash-ci / mix dialyzer	3m 39s
ash-ci / mix test	1m 3s
ash-ci / mix deps.unlock --check-unused	37s
ash-ci / Deploy docs to GitHub pages.	0s
ash-ci / Release	0s
	11m 27s

Provide feedback