feat: viem signing hex or uint8array

[azf20]

What changed?

Allowed passing of a "hex" or bytes to "signMessage" for Viem & Viem-derived Wallet Providers

Why was this change implemented?

Currently Viem signing only supports strings. Viem itself can support Uint8Array & Hex (code, docs).

As the evmWalletProvider doesn't support the { raw: <input> }, we cast everything to a hex string based on the following logic and pass it into raw:

    const hexMessage =
      typeof message === "string" ? (isHex(message) ? message : toHex(message)) : message;

    return this.#walletClient.signMessage({
      account,
      message: { raw: hexMessage },
    });

This is to enable signing Hex messages as well as bytes (e.g. transaction hashes - this came up while trying to sign Gnosis Safe messages) - which otherwise get "hex'd" again by Viem when passed as string messages.

cc @escottalexander

[cb-heimdall]

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