feat: add utilities for testing persistence #19

Job	Run time
prepare	5s
Rust fmt	14s
Check no_std	17s
Check WASM	40s
Build & Test (1.88.0, true, --all-features)	3m 27s
Build & Test (1.75.0, --no-default-features --features miniscript/no-std,bdk_chain/hashbrown)	1m 17s
Build & Test (1.63.0, --all-features)	3m 56s
Build & Test (1.88.0, true, --no-default-features --features miniscript/no-std,bdk_chain/hashbrown)	1m 4s
Build & Test (1.63.0, --no-default-features --features miniscript/no-std,bdk_chain/hashbrown)	1m 45s
Rust clippy	24s
Build & Test (1.75.0, --all-features)	3m 43s
Build & Test Examples (example_bitcoind_rpc_polling)	38s
Build & Test Examples (example_cli)	23s
Build & Test Examples (example_electrum)	55s
Build & Test Examples (example_esplora)	54s
	19m 42s

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