feat!: Resolve OpaqueOps and CustomType extensions #2776

Job	Run time
Check for changes	5s
tests (Rust stable, no features)	1m 35s
Build benchmarks 🏋️	1m 58s
check	1m 35s
tests (Rust 1.75)	2m 38s
tests (Rust beta)	2m 37s
tests (Rust stable, all features)	2m 39s
tests (Rust nightly, coverage)	3m 15s
tests hugr-llvm	0s
Check standard extensions	11s
Required checks 🦀	1s
	16m 34s

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