add DRUPAL_CORS variable

[noahwsmith]

Addresses #333

The goal here is to add a .env variable that will allow setting a CORS value for Drupal without bindmounting the drupal.fpm.conf.tmpl file.

[joecorall]

@noahwsmith - is this needed for static assets? Or can https://www.drupal.org/node/2715637 be used?

[noahwsmith]

Hi Joe- I tested that and it turned out it worked well. I'll close out this Issue and PR.

We had previously had issues with multiple domains, but the current cors service syntax now allows what we need. For posterity, here is a working config that folks can adopt if they find this issue and have a similar need:

parameters:
  cors.config:
    enabled: true
    # Configure requests allowed from specific origins by commenting this out. All domains by uncommenting.
    #allowedOrigins: ['*']
    # Configure requests allowed from multiple origins matching against regex patterns.
    # You shouldn't allow "*" above if you're using Patterns also. Example patterns:
    allowedOriginsPatterns: ['/(.*\.traefik\.me|.*\.sitedomain\.edu|mirador.*\.netlify\.app)/']