Refactor: Move transaction testing utilities from `crates/chain/tests/common` to `testenv` crate #6145

Job	Run time
Check WASM	3m 38s
Check no_std	2m 52s
Build & Test Examples (example_cli)	2m 45s
Build and test (stable, true, --no-default-features --features miniscript/no-std)	4m 33s
Build & Test Examples (example_bitcoind_rpc_polling)	39s
Rust fmt	10s
Build and test (stable, true, --all-features)	4m 5s
prepare	3s
Build & Test Examples (example_electrum)	56s
Build and test (1.63.0, --no-default-features --features miniscript/no-std)	6m 8s
Build & Test Examples (example_esplora)	56s
Build and test (1.63.0, --all-features)	5m 38s
Build & Test Examples (example_wallet_electrum)	49s
Build & Test Examples (example_wallet_esplora_async)	1m 3s
Build & Test Examples (example_wallet_esplora_blocking)	56s
Build & Test Examples (example_wallet_rpc)	38s
clippy_check	3m 43s
	39m 32s

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