Make EntityPrototype.tile_buildability_rules also search entity collision masks

[protocol_1903]

As in title, tile_buildability rules should support all collision mask sources and not just tiles. This would be really nice for creating things like wind turbines that can't be in a certain distance from other wind turbines but other entities can be nearby.

[Osmo]

Not sure if this would be fitting for tile buildability rules, but having a similar way to restrict placement based on entities around would be handy, especially for showing the valid placement spots to the user as highlighting entities green/red based on cursor position isn't something mods can do

[protocol_1903]

Not sure if this would be fitting for tile buildability rules, but having a similar way to restrict placement based on entities around would be handy, especially for showing the valid placement spots to the user as highlighting entities green/red based on cursor position isn't something mods can do

Rather, I think it should be renamed to something like buildability_rules and cover both cases. Or add entity_buildability_rules but checking collision layers twice seems excessive.