Describe the bug

Related to Content Management System (CMS) added in #5106.

We should add an option to allow sites to disable the editing of dspace.cms.home-news because we do not want this section to be edited on https://sandbox.dspace.org.

The setting could be added to the existing homePage settings in config.*.yml similar to:

homePage:
  # When set to `true` (default), the `dspace.cms.home-news` section should be possible to edit from the "Edit CMS Metadata" admin menu.
  # When set to false, that section will not appear for editing.
  editHomeNews: true

This change would be considered a bug fix because it's necessary to allow us to retain a consistent homepage news on our Demo Site.

Related work

Related to #5106.