Flags an entity as using custom lua defined collisions. Fixes entities having spongy player collisions or not hitting traces, such as after Entity:PhysicsFromMesh
Internally identical to
Entity:AddSolidFlags( bit.bor( FSOLID_CUSTOMRAYTEST, FSOLID_CUSTOMBOXTEST ) )
Do not confuse this function with Entity:SetCustomCollisionCheck, they are not the same.
Creates a mesh table, and assigns it as the entity's collisions