When bumping transmission with an unpaid invoice(s), cancel the unpaid invoice(s) and put total amount in new "bumped" lightning invoice.

[bteitelb]

When an invoice is unpaid, and users bump, the original invoice should be cancelled, and the new invoice should include the new amount (not the difference between the original and bumped rate).

For example, user submits 1kb transmission for 50 mSats per byte (i.e. 50,000 mSat invoice). User then bumps the transmission to 100 mSats per byte. The old invoice would be cancelled and the new invoice from bumping would be 100,000 mSats.