feat: Print []+[] as Bool and [] as Unit in user-facing messages (#1745) #2860

Job	Run time
Check for changes	7s
check	2m 8s
Build benchmarks 🏋️	3m 18s
tests (Rust 1.75)	4m 0s
tests (Rust stable, all features)	3m 18s
tests (Rust beta)	3m 33s
tests hugr-llvm (14.0, 14-0)	2m 12s
tests (Rust stable, no features)	2m 26s
tests (Rust nightly, coverage)	4m 34s
Check standard extensions	4s
Required checks 🦀	1s
	25m 41s

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