Create content disposition filename extractor and deprecate duplicate code in REST and JSON API

• Creates the content disposition filename parser
• Replaces usage in REST module
• Replaces usage in JSON API module

"Module-defined constant names should also be prefixed by an uppercase spelling of the module that defines them."

That makes sense if it's in a *.module file, but this will always be called with \Drupal\file\Upload\ContentDispositionFilenameParser::REQUEST_HEADER_FILENAME_REGEX which clearly shows the module and the class it comes from.

In regards to the CR, I wasn't sure if this issue actually justified one. I don't think there is a before and after needed as no one is calling this code. Its an internal protected method that is duplicated in two places: TemporaryJsonapiFileFieldUploader and FileUploadResource. This issue removes the duplication into shared code.

Blocking a critical #2940383: [META] Unify file upload logic of REST and JSON:API therefore this is also critical.

I changed this to a static method, as we are only using the FileSystem dependency for the basename method. And since we are just parsing a filename in content disposition header, we don't need to support StreamWrappers. Therefore the standard PHP basename function should be fine.

One less service to inject!

Re-rolled