feat(hugr-py): builder ops separate from serialised ops #878

Job	Run time
Check for changes in Rust files	7s
Build benchmarks 🏋️	5m 59s
tests (Rust 1.75)	2m 29s
check	1m 37s
tests (Rust beta)	2m 32s
tests (Rust nightly-2024-05-22)	2m 3s
tests (Rust stable, all features)	1m 55s
tests (Rust stable, no features)	1m 50s
Required checks 🦀	1s
coverage	3m 11s
	21m 44s

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