feat: added `electrsd` support for `TestEnv` #8

Job	Run time
Check no_std	38s
Build and test (stable, true, --no-default-features)	1m 24s
Check WASM	1m 7s
Build and test (stable, true, --all-features)	1m 23s
Build and test (1.57.0, --no-default-features)	1m 4s
clippy_check	6m 11s
Rust fmt	20s
Build and test (1.57.0, --all-features)	1m 12s
	13m 19s

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