feat: splitting signing methods into prepare and sign

[howydev]

Pull Request Checklist

• Did you add new tests and confirm existing tests pass? (yarn test)
• Did you update relevant docs? (docs are found in the site folder, and guidelines for updating/adding docs can be found in the contribution guide)
• Do your commits follow the Conventional Commits standard?
• Does your PR title also follow the Conventional Commits standard?
• If you have a breaking change, is it correctly reflected in your commit message? (e.g. feat!: breaking change)
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PR-Codex overview

This PR focuses on enhancing the signing methods for accounts in the smart contract system by introducing prepareSign and formatSign methods, improving error handling, and ensuring compatibility with different signature request types.

Detailed summary

• Added assertNeverSignatureRequestType function to handle invalid signature request types.
• Introduced prepareSign and formatSign methods in various components for consistent signature handling.
• Updated signMessage and signTypedData methods to utilize the new signing methods.
• Enhanced error messages for unsupported versions.
• Modified SignatureRequest and SigningMethods types to accommodate new functionality.
• Improved handling of deferred actions in signing methods.

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