Dedup DecodeHexAddress and DecodeEthHex

[danwt]

https://github.com/dymensionxyz/hyperlane-cosmos/blob/89bed40d16e362c92c12166aa0f86f3db42b3db7/util/hex_address.go#L72

https://github.com/dymensionxyz/hyperlane-cosmos/blob/89bed40d16e362c92c12166aa0f86f3db42b3db7/util/eth_signing.go#L48

There needn't be two right?

It's confusing.

[mbreithecker]

Hey, the name HexAddress is a bit misleading. We realized that later. A proper name would probably be "32BytesAddress" or something similar. The DecodeEthHex allows for decoding arbitrary length hex, whereas the one in HexAddress requires a 32 bytes address.