config: add new `docstring-code-format` knob #22625

Job	Run time
mkdocs	2m 31s
pre-commit	50s
cargo fmt	24s
Determine changes	8s
python package	1m 13s
cargo fuzz	4m 27s
cargo test (linux)	4m 22s
benchmarks	10m 10s
cargo clippy	1m 48s
cargo test (wasm)	1m 10s
cargo udeps	1m 57s
formatter instabilities and black similarity	4m 4s
cargo test (windows)	4m 29s
test scripts	1m 7s
ecosystem	12m 49s
test ruff-lsp	18s
	51m 47s

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