[`refurb`] Implement `int-on-sliced-str` (`FURB166`) #26548

Job	Run time
python package	1m 27s
cargo fmt	20s
Determine changes	12s
pre-commit	37s
mkdocs	2m 17s
cargo fuzz	4m 55s
cargo clippy	1m 56s
benchmarks	4m 26s
cargo test (linux)	3m 27s
cargo test (wasm)	1m 19s
cargo test (windows)	7m 40s
formatter instabilities and black similarity	0s
cargo udeps	1m 52s
test scripts	53s
ecosystem	9m 6s
test ruff-lsp	17s
	40m 44s

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