Support MSC4140: Delayed events (Futures) (#17326) #3315

Job	Run time
check-lockfile	4s
lint-crlf	5s
changes	3s
lint-newsfile	0s
check-sampleconfig	48s
lint	27s
lint-clippy	17s
check-schema-delta	42s
Typechecking	1m 13s
lint-pydantic	41s
lint-readme	8s
lint-clippy-nightly	29s
lint-rustfmt	26s
linting-done	1s
calculate-test-jobs	7s
complement (monolith, SQLite)	12m 48s
trial-olddeps	8m 46s
trial-pypy	0s
complement (monolith, Postgres)	13m 47s
portdb (3.8, 11)	3m 7s
complement (workers, Postgres)	21m 5s
portdb (3.11, 15)	3m 7s
cargo-bench	0s
cargo-test	0s
sytest (focal)	8m 38s
trial (3.8, sqlite, all)	5m 47s
sytest (focal, postgres)	10m 30s
sytest (focal, multi-postgres, workers)	13m 32s
trial (3.9, sqlite, all)	5m 39s
sytest (focal, multi-postgres, workers, asyncio)	18m 56s
trial (3.10, sqlite, all)	5m 50s
sytest (focal, asyncio)	10m 32s
trial (3.11, sqlite, all)	4m 22s
sytest (focal, postgres, asyncio)	11m 35s
trial (3.12, sqlite, all)	4m 52s
trial (3.8, postgres, 11, all)	13m 35s
sytest (testing, postgres)	12m 1s
trial (3.12, postgres, 16, all)	12m 48s
trial (3.8, sqlite)	5m 59s
export-data	2m 8s
tests-done	4s
	3h 34m 59s

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