feat: add `invert` to FFI and Python #1269

Job	Run time
Check python formatting	7s
Check rust formatting	18s
Fetch or Build OpenFST (ubuntu-latest)	7s
Fetch or Build OpenFST (macos-13)	12s
rust-doc	17s
python-doc	1m 16s
rust-clippy	18s
rustfst-python (ubuntu-latest)	1m 2s
rustfst-python (macos-13)	1m 10s
rustfst-python-bench	2m 32s
rust-tests (1.74.0, ubuntu-latest, --all --benches --examples --bins --tests)	2m 16s
rust-tests (1.74.0, ubuntu-latest, --manifest-path rustfst/Cargo.toml --features "state-label-u32")	2m 8s
rust-tests (1.74.0, macos-13, --all --benches --examples --bins --tests)	4m 49s
rust-tests (1.74.0, macos-13, --manifest-path rustfst/Cargo.toml --features "state-label-u32")	3m 4s
rust-tests (stable, ubuntu-latest, --all --benches --examples --bins --tests)	2m 20s
rust-tests (stable, ubuntu-latest, --manifest-path rustfst/Cargo.toml --features "state-label-u32")	2m 16s
rust-tests (stable, macos-13, --all --benches --examples --bins --tests)	3m 33s
rust-tests (stable, macos-13, --manifest-path rustfst/Cargo.toml --features "state-label-u32")	4m 45s
Publish rustfst-python's doc	0s
Publish Rust Crate to Crates.io	0s
Publish Python Wheels to PyPI	0s
	32m 30s

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