feat: executor, testing utilities, and improved tests #125

Job	Run time
Rustfmt	23s
cargo clippy	1m 9s
cargo test (gadget-blueprint-proc-macro)	7m 18s
cargo test (gadget-blueprint-proc-macro-core)	5m 3s
cargo test (gadget-context-derive)	9m 15s
cargo test (gadget-client-eigenlayer)	3m 8s
cargo test (gadget-client-evm)	3m 0s
cargo test (gadget-client-tangle)	2m 20s
cargo test (gadget-crypto-sp-core)	1m 32s
cargo test (gadget-crypto-ed25519)	47s
cargo test (gadget-crypto-bls)	1m 3s
cargo test (gadget-crypto-k256)	55s
cargo test (gadget-crypto-sr25519)	51s
cargo test (gadget-event-listeners-core)	52s
cargo test (gadget-event-listeners-evm)	2m 53s
cargo test (gadget-event-listeners-cronjob)	59s
cargo test (gadget-event-listeners-tangle)	3m 31s
cargo test (gadget-blueprint-serde)	1m 50s
cargo test (gadget-config)	1m 14s
cargo test (gadget-executor)	35m 0s
cargo test (gadget-keystore)	4m 5s
cargo test (gadget-std)	1m 0s
cargo test (gadget-utils-tangle)	2m 7s
cargo test (gadget-networking)	30m 13s
	2h 0m 28s

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