Allow flush dispatcher cache script to accept more subfolders in docroot

[veldotshine]

Is your feature request related to a problem? Please describe.

As defined in manifests/action_flush_dispatcher_cache.pp, it ONLY cleans up the content from the subfolders listed. So we cannot say the dispatcher cache is completely cleaned up. For eg: etc.clientlibs folder is not part of this list and it doesn't get cleaned up when a flush dispatcher cache task is triggered. User will still see old version of the file even after the flush dispatcher cache task is completed.

  "${docroot_dir}/apps",
  "${docroot_dir}/bin",
  "${docroot_dir}/conf",
  "${docroot_dir}/content",
  "${docroot_dir}/etc",
  "${docroot_dir}/home",
  "${docroot_dir}/libs",
  "${docroot_dir}/system",
  "${docroot_dir}/tmp",
  "${docroot_dir}/var"

It is also important not to clean up the docroot_dir (/var/www/html) completely, as it can contain non aem content which doesn't need to be cleaned up.

What is the impact if /var/www/html/etc.clientlibs still contain the old code
When it still have the old code, any frontend changes will not work as expected. For eg if the dev has made a style change, with the old code the dev cannot see the style change in website.

Describe the solution you'd like
Its not possible to define all the subfolders to be cleaned up part of flush dispatcher cache, so it would be great if we can define the list of folders to be cleaned through config.
Can we also include an option to clean up the docroot_dir completely and it can be controlled through config as well. Teams who do not capture non aem content in docroot_dir can use this option, rather maintaining a big list subfolders to be cleaned up.

Describe alternatives you've considered
none