Adapt .nif import to Blender 4+ API

[drvictorvs]

@niftools/blender-niftools-addon-reviewer

Overview

Adapts import for Blender 4+

Detailed Description

[List of functional updates]

Fixes Known Issues

[Ordered list of issues fixed by this PR]

Documentation

[Overview of updates to documentation]

Testing

[Overview of testing required to ensure functionality is correctly implemented]

Manual

[Set of steps to manually verify updates are working correctly]

Automated

[List of tests run, updated or added to avoid future regressions]

Additional Information

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