Active vertex color export

[Blood-Machine]

Noticed that setting vertex color in the exporter to "active' seems to do nothing, or at least not exporting alpha in any capacity so had it default to exporting active vertex color and vertex alpha if this setting is chosen

There's another instance of gltf_vertex_color == ACTIVE being used elsewhere,as well as double implementation of "gltf_active_vertex_color_when_no_material' is True" seemingly, so I reimplemented this simply next to the seemingly functional reimplementation of "gltf_active_vertex_color_when_no_material' is True" with just a conditional

[CLAassistant]

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[Blood-Machine]

Hi, sorry, just run up against it behaving inconsistently. When previously exporting with the "active" vertex colour export, it wouldn't export alpha properly, but now it seems to be behaving correctly without any alteration to the code. Will verify, sorry for the bother