Text filter to only show first content page if current route is not that entity route

WIP, I'm stuck because of #3360216.

This works, though it takes a bit of finagling to make it work correctly due to #3360216.

In order to make #3 work I had to manually modify the config file for the text format like this:

  filter_html:
    id: filter_html
    provider: filter
    status: true
    weight: -48
    settings:
      allowed_html: '<br> <p class="text-align-left text-align-center text-align-right text-align-justify"> <h2 class="text-align-left text-align-center text-align-right text-align-justify"> <h3 class="text-align-left text-align-center text-align-right text-align-justify"> <h4 class="text-align-left text-align-center text-align-right text-align-justify"> <h5 class="text-align-left text-align-center text-align-right text-align-justify"> <h6 class="text-align-left text-align-center text-align-right text-align-justify"> <strong> <em> <s> <sub> <sup> <blockquote> <a href data-entity-type data-entity-uuid data-entity-substitution> <ul> <ol reversed start> <li> <hr> <drupal-media data-entity-type data-entity-uuid alt data-caption data-align> <div class="page-break" style="page-break-after"> <span style="display">'
      filter_html_help: false
      filter_html_nofollow: false

The new bits are the DIV and SPAN items at the end.

It's worth noting that the plugin in #3 looks for <div class="page-break" rather than the full string provided by the Pagebreak plugin.

Now with the config file I forgot to add before. I also renamed the plugin to be more specific.

Moving to the CKEditor 5 Plugin Pack module.

The patch needs to be rerolled.

Rerolled.