Introduce `TransactionVerifier` #382

Job	Run time
Clippy	45s
Test Rust stable on ubuntu	4m 57s
Test Rust nightly on ubuntu	5m 32s
rustfmt	6s
no-std (stable, wasm32-unknown-unknown)	1m 1s
no-std (nightly, wasm32-unknown-unknown)	1m 29s
	13m 50s

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