Add eth_getRawTransactionByHash

[kclowes]

What was wrong?

We don't have support for the eth_getRawTransactionByHash RPC method.

How can it be fixed?

Add it to BaseEth, and add it to both Eth and AsyncEth following established patterns. Tests will need to be added as well.

[Moras-del]

Hello! I would like to work on this. Could you assign this task to me? :)

[kclowes]

Done! Let me know if you need any guidance! PR-ing early and often is best! Thanks!

[kclowes]

Fixed in #2051