Update makefsdata.py to support content encoding Fixes #2548 (#2549)

* Update makefsdata.py to support content encoding

changed makefsdata.py slightly to allow it to recognize files that have been manually gzipped (e.g. "mysite.css.gz") to send the proper Content-Encoding information in the response headers.

* Code review fix

---------

Co-authored-by: Peter Harper <peter.harper@raspberrypi.com>

src/rp2_common/pico_lwip/tools/makefsdata.py

@@ -19,7 +19,7 @@ def process_file(input_dir, file):
     results = []
 
     # Check content type
-    content_type, _ = mimetypes.guess_type(file)
+    content_type, content_encoding = mimetypes.guess_type(file)
     if content_type is None:
         content_type = "application/octet-stream"
 
@@ -53,9 +53,15 @@ def process_file(input_dir, file):
         comment = f"\"Content-Length: {file_size}\" ({len(data)} chars)"
         results.append({'data': bytes(data, "utf-8"), 'comment': comment});
 
-    # content type
+    # content type and content encoding
-    data = f"Content-Type: {content_type}\r\n\r\n"
+    content_type_header = f"Content-Type: {content_type}"
-    comment = f"\"Content-Type: {content_type}\" ({len(data)} chars)"
+    if content_encoding is None:
+        data = f"{content_type_header}\r\n\r\n"
+        comment = f"\"{content_type_header}\" ({len(data)} chars)"
+    else:
+        content_encoding_header = f"Content-Encoding: {content_encoding}"
+        data = f"{content_type_header}\r\n{content_encoding_header}\r\n\r\n"
+        comment = f"\"{content_type_header} {content_encoding_header}\" ({len(data)} chars)"
     results.append({'data': bytes(data, "utf-8"), 'comment': comment});
 
     # file contents