Add function to disable props collision only for player class

[Isemenuk27]

e2function void entity:noCollidePlayers(state)
    if not IsValid(this) then return self:throw("Invalid entity!", nil) end
    if not isOwner(self, this) then return self:throw("You do not own this prop!", nil) end

    this:SetCollisionGroup(state == 0 and COLLISION_GROUP_NONE or COLLISION_GROUP_PASSABLE_DOOR)
end

It will be useful for vehicles construction.

[Denneisk]

I feel like there should just be a general entity:setCollisionGroup function.

[vurvdev]

Resolved by #2750