Add payee shortcut to frontend

[dumbPy]

Just like pressing n allows editing narration, there should be a "press p to edit/add and edit" payee.
From the transaction_line_editor.tsx, I think it should be trivial given you already have payeeStart and payeeEnd indexes tracked in TransactionLineParseResult and there's editNarration method for reference.
That being said, I have sparingly worked on frontends and this would need a lot of effort setting up for me. :disappointed:
Would be great if someone could add it.