Move rewritten blend files instead of copying them

This will cause a nice speedup if the temporary directory happens to be on
the same file system as the target directory for the BAT Pack. This can be
influenced by setting an environment variable; see the documentation for
[tempfile.gettempdir](https://docs.python.org/3/library/tempfile.html#tempfile.gettempdir)

blender_asset_tracer/cli/pack.py

@@ -36,7 +36,7 @@ def cli_pack(args):
         packer.execute()
     except pack.queued_copy.FileCopyError as ex:
         log.error("%d files couldn't be copied, starting with %s",
-                  len(ex.files_not_copied), ex.files_not_copied[0])
+                  len(ex.files_remaining), ex.files_remaining[0])
         raise SystemExit(1)