Fix invalid file path handling in Windows when there is dot in the file name

This basically re-adds dot-removal removed by the previous commit.

drivers/windows/file_access_windows.cpp

@@ -60,7 +60,12 @@ void FileAccessWindows::check_errors() const {
 
 bool FileAccessWindows::is_path_invalid(const String &p_path) {
 	// Check for invalid operating system file.
-	String fname = p_path.get_file().get_basename().to_lower();
+	String fname = p_path.get_file().to_lower();
+
+	int dot = fname.find(".");
+	if (dot != -1) {
+		fname = fname.substr(0, dot);
+	}
 	return invalid_files.has(fname);
 }