Rename LedgerEntryType `Emitted` to `EmittedTxn`

[Mwni]

This would be more descriptive and in line with the other ledger object type names, like

• AccountRoot
• DirectoryNode
• NFTokenPage

[RichardAH]

I agree with this but I won't change it (yet) until I have better unit testing place

[Mwni]

Yes!