feat: added `electrum` and `esplora` support to `TestEnv` #23

Job	Run time
Check WASM	36s
Check no_std	29s
Build and test (stable, true, --no-default-features)	3m 38s
clippy_check	7m 21s
Build and test (stable, true, --all-features)	3m 15s
Rust fmt	11s
Build and test (1.57.0, --no-default-features)	5m 8s
Build and test (1.57.0, --all-features)	6m 14s
	26m 52s

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