[feature] Able to set a custom DXVK version

[ranplayer]

Feature Request

I confirm:

• that I haven't found another request for this feature.
• that I have checked whether there are updates for my system available that
  contain this feature already.

Description

It would be useful if a custom DXVK version could be set per game.

Justification

Some DXVK versions present regressions in some games, like Bayonetta running on Proton 5.13 (other D3D9 games might be facing the same issue). If you just change the Proton build from a previous version, you might loose bug fixes and performance improvements related to Wine.

[kisak-valve]

Hello @ranplayer, I think the intent for #4201 applies here. Regressions in DXVK or other sub-components of Proton should always be reported and fixed, not avoided. There are methods to swap out the version DXVK in use, but that shouldn't be considered supported.

[ranplayer]

@kisak-valve , I agree with you. The thing is: fixes may take time to be available for the final users, and in the meantime an easier workaround mechanism would be useful. I've been tracking some Proton regressions that took more than 6 months to get fixed (like this one from Killer Instinct).

Anyway, I just like to express here that I really enjoy this project and all the hard work from people involved.