Expose linking functionality at IThirdwebWallet level

[0xFirekeeper]

Improve dx, less casting requirements
Also removes the need to call SmartWallet.GetPersonalWallet to fetch linked accounts or link new ones with its signer

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PR-Codex overview

This PR focuses on enhancing the account linking functionality across various wallet implementations in the Thirdweb library. It introduces new methods for linking accounts and retrieving linked accounts while updating existing methods to support a more generalized wallet interface.

Detailed summary

• Added LinkAccount and GetLinkedAccounts methods to IThirdwebWallet.
• Implemented LinkAccount and GetLinkedAccounts methods in SmartWallet.
• Updated LinkAccount in InAppWallet and EcosystemWallet to accept IThirdwebWallet.
• Added validation for wallet types in SmartWallet and updated error handling.
• Enhanced argument checks in LinkAccount methods across wallet classes.

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