Array support in encodeData for EIP712 signature.

[Amxx]

I have been working with metamask support of EIP712 signatures for a long time, but when I recently tryied signing an array of structs I got an error:

```RPC Error: Error: MetaMask Message Signature: Error: Arrays currently unimplemented in encodeData`` `

To reproduce the error, just run the following code:

TYPES =
{
	EIP712Domain: [
		{ name: "name",              type: "string"  },
		{ name: "version",           type: "string"  },
		{ name: "chainId",           type: "uint256" },
		{ name: "verifyingContract", type: "address" },
	],
	Entry: [
		{ name: "id",                 type: "address" },
		{ name: "value",              type: "uint256" },
	],
	Entries: [
		{ name: "content",            type: "Entry[]" },
	],
};
DOMAIN =
{
	name:              "test-domain",
	version:           "0.0.1",
	chainId:           await web3.eth.net.getId(),
	verifyingContract: 0,
};
wallet = "0x......."; // Your wallet address here
message = { content: [{ id: 0, value: 0 }] };
await web3.currentProvider.sendAsync({
	method: "eth_signTypedData_v3",
	params: [ wallet, JSON.stringify({ types: TYPES, domain: DOMAIN, primaryType: "Entries", message: message }) ],
	from: wallet,
});