Cannot remap _ since not in the remap key list

### Microsoft PowerToys version

0.97.0

### Installation method

GitHub

### Area(s) with issue?

Keyboard Manager

### Steps to reproduce

Looking for _ in the remap list : Not Present
Pressing _ not appearing too

### ✔️ Expected Behavior

_ available

### ❌ Actual Behavior

Not present in the list

### Additional Information

I have an Azerty keyboard not a Qwerty so _ is not made with a combination of key but number are and i already tried to disable the 8.

### Other Software

_No response_

Start by reproducing the missing underscore in Keyboard Manager with an Azerty keyboard and trace how the remap key list is built. The issue provides no file or test entry point; done means underscore is available for remapping and the behavior is covered by an appropriate regression check.

Written by the indexing model from the issue text.