bugfix [#23194] export UVs miss the extension file

also made all other exporters do this.

Made some internal changes.
- moved path functions from bpy.utils to bpy.path (similar to os.path)
- added functions...
  bpy.path.ensure_ext(path, ".ext", case_sensitive=False) # simple function to ensure the extension is set.
  bpy.path.resolve_ncase(path) # useful for importing scenes made on windows where the path case doesnt match the files.

source/blender/python/doc/sphinx_doc_gen.py

@@ -360,6 +360,7 @@ def rna2sphinx(BASEPATH):
     
     # py modules
     fw("   bpy.utils.rst\n\n")
+    fw("   bpy.path.rst\n\n")
     fw("   bpy.app.rst\n\n")
     
     # C modules
@@ -440,6 +441,9 @@ def rna2sphinx(BASEPATH):
     from bpy import utils as module
     pymodule2sphinx(BASEPATH, "bpy.utils", module, "Utilities (bpy.utils)")
 
+    from bpy import path as module
+    pymodule2sphinx(BASEPATH, "bpy.path", module, "Path Utilities (bpy.path)")
+
     # C modules
     from bpy import app as module
     pymodule2sphinx(BASEPATH, "bpy.app", module, "Application Data (bpy.app)")