Detect implicit returns in auto-return-types #22247

Job	Run time
cargo fmt	15s
Determine changes	7s
pre-commit	25s
python package	1m 9s
mkdocs	2m 9s
cargo test (wasm)	1m 10s
cargo clippy	1m 53s
cargo test (linux)	3m 29s
cargo test (windows)	5m 40s
cargo udeps	1m 51s
cargo fuzz	4m 28s
formatter instabilities and black similarity	3m 32s
test scripts	47s
benchmarks	9m 51s
test ruff-lsp	16s
ecosystem	11m 23s
	48m 25s

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