circuits: Add `TxCircuit::from_slice` constructor #439

Job	Run time
Code Analysis / Rust Format	11s
Code Analysis / Clippy Check	13s
test cirucits / Run tests	3m 5s
Dusk Analyzer / Dusk Analyzer	11s
test core / Run tests	11s
test core rkyv compiles / Run tests	12s
	4m 3s

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