Add logging level control for gltf exports

[buildxyz-git]

Issue: Exporting scene as gltf when using python built as a module is very noisy with INFO logging entries.

I have made changes to ExportGLTF2_Base in:
blender/scripts/addons_core/io_scene_gltf2/__init__.py

changes support setting the log level instead of using the hardcoded INFO value here which produces way to much output when exporting.

ImportGLTF2 already has a pattern for this here so I created a global set_debug_level function they can both use in the same manner.

The user can now set the log level before exporting by setting bpy.app.debug_value like:

bpy.app.debug_value = 2
bpy.ops.export_scene.gltf(...)

This will solve issue 2267

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[julienduroure]

Thanks for the PR
I will have a look soon

[julienduroure]

Merged, thanks!