feat!: `used_extensions` calls for both ops and signatures #2817

Job	Run time
Check for changes	5s
tests (Rust stable, all features)	2m 19s
check	1m 12s
tests (Rust nightly, coverage)	4m 3s
Build benchmarks 🏋️	1m 53s
tests (Rust 1.75)	2m 17s
tests (Rust stable, no features)	1m 24s
tests (Rust beta)	2m 33s
tests hugr-llvm	0s
Check standard extensions	4s
Required checks 🦀	1s
	15m 51s

Provide feedback