Casting to MsgEthereumTx in rpc not working for txs before v36

[skosito]

Describe the Bug
We should cast to etherminttypes.MsgEthereumTx as fallback. Some funcs are missing on legacy MsgEthereumTx in evm module that should be added (eg. AsTransaction())

To Reproduce

eth_getBlockByNumber

testnet block: 4338639, only 2 synthetic txs present instead of 3

mainnet block: 2328117, 0 tx returned

Expected Behavior
All txs should be returned properly

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Environment (please complete the following information):

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