Add support for WBMP file format

[SheerGeyser]

1. Specify the MIME type and extension for which to add support
   image/vnd.wap.wbmp

2. Share an example file
   GitHub: File type not allowed: .wbmp

3. Optionally, add a reference to the specification of the file format.
   https://www.online-convert.com/file-format/wbmp