feat(bitfield): add `u128` support #1312

Job	Run time
changed_paths	6s
Loom tests (cordyceps)	7m 1s
cargo check (host)	7m 48s
clippy	6m 49s
build boot image (x86_64)	7m 15s
Miri tests (codyceps)	6m 6s
docs	8m 33s
Loom tests (maitake)	7m 58s
Tests (maitake, no-default-features)	5m 33s
rustfmt	14s
cargo test (host)	8m 49s
cargo test (cross x64)	8m 14s
Loom tests (mycelium-util)	4m 39s
	1h 19m 5s

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