Add Support for App Router Invalidation by Tag in Drupal Module

[backlineint]

Package

next (Drupal module)

Describe the feature request

This is a follow up to the discussion in #763 and #797

Similar to the module's path based revalidation, we should update the module to call our revalidation endpoint for the app router's revalidation by tag.

Describe the solution you'd like

• For a next.js entity type (the config entity) we'd need to add a new plugin option under on-demand revalidation to select if we should invalidate by tag.
• modules/next/modules/next_extras/src/NextCacheInvalidator.php will need new getTagsToInvalidate and invalidateTags methods.
  ** The invalidateTags method will make an API call to the revalidation endpoint, and pass a comma separated list of all cache tags using the tags parameter. (Updates to FE API route are outlined here: feat(next-drupal): next revalidate options #784)
• invalidateEntity will need to add conditional logic to check for the invalidation type and adjust accordingly.
• getRevalidateUrlforPath needs to be made more generic - currently it always adds the path query string parameter.

Describe alternatives you've considered

A page router based approach was implemented here: #797

[backlineint]

@minnur we merged the updates to API routes that this will depend on. As outlined here, the tags param is comma separated. I tested that it will work if either encoded or not encoded. As you dig in, curious if you think comma separated makes the most sense here. Would be a pretty easier change if another delimiter makes more sense.