Add a cvar that would allow projectiles to collide with playerclips

[Natanxp2]

Is your feature request related to a problem?

Many surf maps use models + playerclips instead of brushes for ramps.
Adding an option like that would make those maps playable in weapon modes

Describe the solution you'd like

Adding a cvar protected by sv_cheats would probably be the simplest solution.
It could potentially be on by default in surf maps so that runs could be uploaded to hidden leaderboards.
It doesn't seem like it would cause any problems since surf doesn't use weapons anyway

Describe alternatives you've considered, if any.

No response

Additional context

No response