[Backport] Allow for injection of new sections in form progress panel

[cjcolvar]

This commit adds a new code seam allowing for adding new sections to the
form progress panel that renders on the right side of the work form.

To add a section in an application override the form_progress_sections_for helper method and make sure it gets loaded
after Hyrax::HyraxHelperBehavoir (by default included in app/helpers/hyrax_helper.rb). For example:

module WorksHelper
  def form_progress_sections_for(*)
    super + ["my_new_section"]
  end
end

Then add a new partial at app/views/hyrax/base/_form_progress_my_new_section.html.erb.

Also in this PR:

• work form helper spec file renamed to match the name of the module tested
• yard docs added for new helper methods with examples

Backport of #4453.

@samvera/hyrax-code-reviewers