move substitute lib to open source (pytorch#79093)

Summary: as title

Test Plan: buck build //xplat/caffe2:generated_aten_config_header

Reviewed By: kit1980

Differential Revision: D36989348

Pull Request resolved: pytorch#79093
Approved by: https://github.com/malfet

Author: linbinyu

tools/substitute.py

@@ -0,0 +1,24 @@
+import argparse
+import os
+import os.path
+
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser()
+    parser.add_argument("--input-file")
+    parser.add_argument("--output-file")
+    parser.add_argument("--install_dir")
+    parser.add_argument("--replace", action="append", nargs=2)
+    options = parser.parse_args()
+
+    with open(options.input_file, "r") as f:
+        contents = f.read()
+
+    output_file = os.path.join(options.install_dir, options.output_file)
+    os.makedirs(os.path.dirname(output_file), exist_ok=True)
+
+    for old, new in options.replace:
+        contents = contents.replace(old, new)
+
+    with open(output_file, "w") as f:
+        f.write(contents)