Release v2.2.6

Patch/v2.2.6 (#72)

* VMT: Fix shader material processing

* func_detail: Add lightmap unwrapping

* prop_static: Set GI mode to static

* light: Update ranges calculation

* Instances: Remove visibility range parameter definition

* prop_static: Move skins applying logic to prop_studio.gd

* Bump v2.2.6

* VMT: Add roughnessfactor2 support for blend materials

* VMT: Fix worldvertextransition material import

* VMF: Fix micro-seams during import

* prop_studio: Fix skin property

* VMT: Update transformer class

* VTF: Extend extensions to import in case VTF is not exist

* Entities: Update group assignment approach

* VMFEntityNode: Update output trigger processing

* VMT: Add material shading changing depending on VMT's shader

* VMT: Add mipmap support for VTF conversion

* VMF: Add option to enable double-sided shadow casting

* QoL: Add option to create blend materials

* VMT: Assign shading_mode only for StandardMaterial3D

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Co-authored-by: catperson6real-dev <catperson6yt.is.back@gmail.com>