Split AdapterOptions

[elpiel]

In #143 the options for both adapters are in 1 struct, separate the struct into 2 structs for each Adapter:

• Dummy Adapter options struct
• Ethereum Adapter options struct

This will ensure not to check for all the required options in the specific adapter and will remove a lot of this code in the init functions.

Another option is to use an Enum and have a default init fn taking it and have a TryFrom<ConfigStructForEthereum> for EthereumAdapter

@samparsky Also for the Keystore file, why don't we just deserialize it into an object instead of keystore_json: Value, and instead of doing let address = match keystore_json["address"].as_str() { .... }; we can ensure that the passed Keystore file is correct and we can use that struct in the Ethereum adapter like keystore: Keystore instead of serde Value