Reuse `BTreeSets` in module resolver #33217

Job	Run time
Determine changes	11s
mkdocs	2m 49s
pre-commit	36s
cargo fmt	19s
python package	1m 29s
cargo build (release)	4m 29s
cargo build (msrv)	3m 22s
benchmarks	4m 58s
cargo clippy	1m 48s
cargo fuzz	5m 24s
cargo shear	25s
cargo test (linux)	3m 51s
cargo test (wasm)	1m 37s
cargo test (windows)	7m 44s
formatter instabilities and black similarity	0s
test scripts	55s
ecosystem	8m 40s
test ruff-lsp	13s
Fuzz the parser	0s
	48m 50s

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