EIP712 doesn't support optional parameters

[hanchon]

System info: Ethermint v0.16.1

Steps to reproduce:

1. To replicate a simple test can be created on app/ante/utils_tests.go

func (suite *AnteTestSuite) CreateTestEIP712MsgEditValidator(from sdk.AccAddress, priv cryptotypes.PrivKey, chainId string, gas uint64, gasAmount sdk.Coins) client.TxBuilder {
	valAddr := sdk.ValAddress(from.Bytes())
	msgEdit := types3.NewMsgEditValidator(
		valAddr,
		types3.NewDescription("moniker", "identity", "website", "security_contract", "details"),
		nil,
		nil,
	)
	return suite.CreateTestEIP712CosmosTxBuilder(from, priv, chainId, gas, gasAmount, msgEdit)
}

2. And call the function in app/ante/ante_test.go inside the TestAnteHandler function

		{
			"success- DeliverTx EIP712 edit validator",
			func() sdk.Tx {
				from := acc.GetAddress()
				coinAmount := sdk.NewCoin(evmtypes.DefaultEVMDenom, sdk.NewInt(20))
				amount := sdk.NewCoins(coinAmount)
				gas := uint64(200000)
				txBuilder := suite.CreateTestEIP712MsgEditValidator(from, privKey, "ethermint_9000-1", gas, amount)
				return txBuilder.GetTx()
			}, false, false, true,
		},

Expected behavior: Test should pass

Actual behavior: Errors with: failed to pack and hash typedData primary type: provided data '<nil>' doesn't match type 'string'. Because it's expecting a string and the interpreter is getting a '<nil>' value.

Additional info: The current implementation doesn't support optionals so sending nil is invalid. The message is working fine if the optional values are set to valid strings

[github-actions[bot]]

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[facs95]

Duplicated https://github.com/evmos/ethermint/issues/1247