Add autotyping-like return type inference for annotation rules #21682

Job	Run time
cargo fmt	12s
cargo clippy	1m 47s
cargo test (linux)	6m 32s
Determine changes	7s
cargo fuzz	6m 35s
cargo test (wasm)	1m 4s
cargo udeps	2m 9s
cargo test (windows)	4m 41s
test scripts	1m 26s
pre-commit	34s
python package	2m 6s
benchmarks	10m 6s
mkdocs	2m 8s
formatter instabilities and black similarity	3m 32s
test ruff-lsp	14s
ecosystem	11m 26s
	54m 39s

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