"You need to select more coins!" when editing a "speed up" transaction

**Describe the bug**
The "Speed up" button allows to "Fully edit the transaction", which is great when there's no change output (#988), but it fails to create the new transaction. It's probably because the inputs of the original transaction are considered spent, and thus don't appear in the coin selection list.

**To Reproduce**
Steps to reproduce the behavior:
1. Have an unconfirmed transaction in a wallet
2. Click on 'Speed up'
3. Enter the new fee rate
4. Click on "Advanced" and "Fully edit the transaction"
5. Notice the inputs of the original transaction don't appear in the coin selection table
6. Click on "Create the unsigned transaction"
7. It says "You need to select more coins!"

**Expected behavior**
- Either the new transaction should be created with the new fee rate and the same inputs,
- or the UI should allow the selection of the same inputs as in the replaced transaction

**Desktop:**
- Where is your node running: local(internal)
- Where is your specter running: binary
- If you're running a binary, which OS: Linux
- Browser: electron
- Specter Version: tested on 2.0.0, 2.0.1, and 2.0.2pre6

**Additional context**
It seems the code checks if there's enough coins selected by looking at the selected rows whereas there's no row for the spent outputs. The internal `selected-coins` list may contain the right coins though.