feat: executor, testing utilities, and improved tests #127

Job	Run time
cargo clippy	1m 7s
Rustfmt	23s
cargo test (gadget-blueprint-proc-macro)	7m 19s
cargo test (gadget-blueprint-proc-macro-core)	4m 59s
cargo test (gadget-context-derive)	9m 24s
cargo test (gadget-client-eigenlayer)	3m 19s
cargo test (gadget-client-evm)	1m 58s
cargo test (gadget-client-tangle)	2m 21s
cargo test (gadget-crypto-sp-core)	1m 28s
cargo test (gadget-crypto-ed25519)	59s
cargo test (gadget-crypto-bls)	1m 2s
cargo test (gadget-crypto-k256)	59s
cargo test (gadget-crypto-sr25519)	52s
cargo test (gadget-event-listeners-core)	50s
cargo test (gadget-event-listeners-evm)	2m 39s
cargo test (gadget-event-listeners-cronjob)	1m 0s
cargo test (gadget-event-listeners-tangle)	2m 32s
cargo test (gadget-blueprint-serde)	1m 51s
cargo test (gadget-config)	1m 8s
cargo test (gadget-executor)	35m 0s
cargo test (gadget-keystore)	3m 47s
cargo test (gadget-std)	1m 3s
cargo test (gadget-utils-tangle)	2m 8s
cargo test (gadget-networking)	2m 13s
	1h 30m 21s

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