Reject potentially malicious mods

[paoloambrosio]

AMS2 mods wouldn't contain exe or dll files. We should skip installation of those files.

Notes:

• While there is a possibility for some mods to contain code, like CSP in AC, the AMS2 modding community is FAR from being able to take advantage of anything like this. When this is reality, we can think of more sophisticated ways of handling it.