* PEP 594 has cgi module scheduled for deprecation in Python 3.8. Reimplement
cgi.parse_header in Sanic. The new implementation is much faster than either
cgi.parse_header or equivalent werkzeug.parse_options_header, and unlike the
two, handles also quoted values with semicolons or \" in them.
* Fix string escape.
* Useless linter complaints.
* More linter issues
* Add return type hint.
* Do not support quoted-pair escapes.
- Improved documentation and renamed the function more aptly as it only seems
to apply to content-type and content-disposition headers.
* Unquote filenames also in normal mode.
* Add tests for headers. Adapted from CPython parse_header tests with changes on the final test.
* Linter
* Revert "Unquote filenames also in normal mode."
This reverts commit bf0d502bcd.
* Improved parse_content_header and added tests with Firefox and Chrome.
- Unescaping of quotes moved to parse_content_header because it affects all fields,
not just filenames.
- It is impossible to handle all cases correctly but the current heuristics should
suffice well for typical cases and beyond.
- Added comparisons with cgi.parse_header and werkzeug.parse_options_header.
* Updated comments as well.
