tests: inject delegation using admin

[gusin13]

Adds test to inject fp and delegation in smart contract using admin

[SebastianElvis]

Tbh I have no idea why this works and cannot tell the difference between the protobuf objects in babylon and these ones, but great work 👍 These are only for testing purposes so hacking around should be fine

[gusin13]

@SebastianElvis so for the fields which are Binary in rust we need to send b64 string from Go, in the protobuf struct for example in case of delegation the staking tx is []bytes ref but we need it to be a string so had to create a custom struct and then b64 encode the staking tx.

[SebastianElvis]

OK, that means we need to avoid []byte completely when submitting ExecMessage to contracts 😢 thanks for figuring this out