[CI] enable code-format-helper for .cl files (llvm#135748)

In clang-format, OpenCL .cl file uses default C++ formatting. There are
many pull-requests in libclc project that change OpenCL files. It is
beneficial to enable clang-format for them in CI.

Author: wenju-he

llvm/utils/git/code-format-helper.py

@@ -186,7 +186,17 @@ def filter_changed_files(self, changed_files: List[str]) -> List[str]:
         filtered_files = []
         for path in changed_files:
             _, ext = os.path.splitext(path)
-            if ext in (".cpp", ".c", ".h", ".hpp", ".hxx", ".cxx", ".inc", ".cppm"):
+            if ext in (
+                ".cpp",
+                ".c",
+                ".h",
+                ".hpp",
+                ".hxx",
+                ".cxx",
+                ".inc",
+                ".cppm",
+                ".cl",
+            ):
                 filtered_files.append(path)
             elif ext == "" and self.should_include_extensionless_file(path):
                 filtered_files.append(path)