Add magazine well retextures

[jonpas]

Magazines on this screenshot should be same as MX_BlackCamo retexture:

Magazine wells split that so we have to apply it to the magazines as well (as in add new classes).

[jonpas]

Scribble:

// CfgMagazines.hpp
class CfgMagazines {
    class MyBlackMagazineClass: 30Rnd_65x39_caseless_mag {
        hiddenSelectionsTextures[] = {"\x\tacs\myBlackMXTexture_co.paa"};
    };
};

// CfgMagazineWells.hpp
class CfgMagazineWells {
    class CBA_65x39_MX {
        ADDON[] = {
            QCLASS(MyBlackMagazineClass)
        };
    };
};

Put into weapons component.

[jonpas]

Partly fixed in #119, keeping this open as ideally we would restore the Black Camo magazines.

[jonpas]

Unit magazines fixed in #121, however proper Black Camo magazines are still not there.