Fix glTF memory issues

[mwestphal]

Describe the bug
There are a few issues in glTF parser:

• Issue #19732 - Heap Buffer Overflow in vtkGLTFImporter::ImportActors
• Issue #19733 - Heap Buffer Overflow in vtkGLTFDocumentLoader::MeshAccess
• Issue #19734 - Heap Buffer Overflow in Scene Node Processing
• Issue #19735 - Heap Use-After-Free in Mesh Name Access
• Issue #19736 - Heap Use-After-Free in Mesh Copy Constructor

Lets fix them all!