[TASK] Context Derives - Defaults and additional options

[Tjemmmic]

Overview

Introduce Derive macros for GadgetConfiguration (Context) to simplify the implementation of common traits and functionalities. These derives will automatically handle boilerplate code, such as the implementation of the keystore, Tangle client, and standard defaults, allowing developers to focus on core logic without manual implementation of repetitive tasks.

Checklist

• WithKeystore: Automatically implement the keystore trait for any struct that derives WithKeystore. This will provide out-of-the-box support for secure key management.
• WithTangleClient: Automatically implement the client function that returns a new subxt::OnlineClient instance for interacting with the Tangle. This will streamline integration with the Tangle network.
• StandardDefaults: (Name will change) Automatically derive a set of common derives (e.g., Default, Clone, Debug, PartialEq) for GadgetConfiguration, reducing the need for manual derivations and ensuring consistency.
• Specific keystore derives for functions specific to each key type e.g., first_ecdsa_signer
• Tests for each Derive
• Document the derives - [TASK] Docs - Context Derive Options #271

[drewstone]

Pseudocode examples would be helpful, but generally I think my first feeling about naming is that I don't like these names or deriving WithKeystore feels off.