feat!: Hugrs now keep a `ExtensionRegistry` with their requirements #2794

Job	Run time
Check for changes	4s
Build benchmarks 🏋️	2m 36s
check	1m 40s
tests (Rust nightly, coverage)	4m 28s
tests (Rust stable, all features)	3m 5s
tests (Rust 1.75)	3m 29s
tests (Rust stable, no features)	2m 17s
tests (Rust beta)	3m 17s
tests hugr-llvm	0s
Check standard extensions	5s
Required checks 🦀	1s
	21m 2s

Provide feedback