REST invalidate cache

This modules adds a simple REST endpoint that invalidates specific cache tags.

It can be useful if you need to invalidate cache tags from an external service.

To use it:

1. Install this module and restui.
2. Browse to /admin/config/services/rest.
3. Enable the Invalidate cache resource and add an authentication method.
4. You can then send a POST request to /invalidate_cache/[comma separated cache tags] to invalidate these cache tags.