add ins formatter

PyTeX/format/ins_formatter.py

@@ -0,0 +1,17 @@
+from .formatting_config import FormattingConfig
+from .pytex_formatter import PyTeXFormatter
+from pathlib import Path
+import shutil
+
+from typing import List, Tuple
+
+
+class InsFormatter(PyTeXFormatter):
+    def output_files(self) -> List[str]:
+        return []
+
+    def format(self, build_dir: Path, overwrite: bool = False) -> List[Tuple[str, FormattingConfig]]:
+        return []
+
+    def dependencies(self) -> List[str]:
+        return []  # TODO