Allow an access list of cookies

Problem/Motivation

I have a site that uses cookies for storing user information that Drupal then uses to display content back to that user.

These custom cookies are stripped out by Fastly once I upload VCL snippets to Fastly as the rules in `vcl_snippets/recv.vcl` explicitly strip out any cookies that aren't the session cookie and auth tokens:

`set req.http.Cookie = regsuball(req.http.Cookie, ";(SimpleSAMLSessionID|SimpleSAMLAuthToken|SESS[a-z0-9]+|SSESS[a-z0-9]+|NO_CACHE)=", "; \1=");`

Steps to reproduce

• Setup a page that sets a custom cookie (can be PHP or JS)
• Setup another page that prints the cookie contents
• Go between pages to see the cookie contents are set and printed
• Click 'Upload VCL snippets to Fastly' in the module
• Go back to the print page and see this is empty, despite the cookie still being present
• If you are logged in then the session cookie is still present

Proposed resolution

Create a field in the settings that allows regexs for cookies that should be allowed through. This can then be prepended to the snippet before its uploaded to Fastly.

Alternately take out this cookie stripping as it will trip people up until they can allow cookies through Fastly.

The quickest fix to stop people tripping over this would be to add a note to the Readme letting users know that the snippet will be used by default and this can have side effects.

Cheers

Tom