Add support for MSC4115 #993

Job	Run time
check-lockfile	4s
changes	3s
lint-newsfile	39s
lint-crlf	5s
Typechecking	1m 28s
lint	48s
lint-clippy	23s
check-schema-delta	49s
check-sampleconfig	43s
lint-clippy-nightly	18s
lint-pydantic	42s
lint-rustfmt	22s
linting-done	3s
calculate-test-jobs	11s
trial-olddeps	6m 56s
portdb (3.8, 11)	2m 55s
complement (monolith, SQLite)	12m 16s
trial-pypy	0s
portdb (3.11, 15)	2m 43s
complement (monolith, Postgres)	13m 11s
complement (workers, Postgres)	20m 52s
cargo-bench	2m 27s
cargo-test	2m 12s
sytest (focal)	9m 48s
trial (3.8, sqlite, all)	4m 24s
sytest (focal, postgres)	11m 25s
sytest (focal, multi-postgres, workers)	16m 17s
trial (3.8, postgres, 11, all)	10m 31s
sytest (focal, multi-postgres, workers, asyncio)	20m 32s
trial (3.8, sqlite)	3m 50s
export-data	2m 9s
tests-done	3s
	2h 29m 9s

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