Change settings area to be separated into categories in admin UI (#19407)

And update all descriptions

app/views/admin/settings/about/show.html.haml

@@ -0,0 +1,33 @@
+- content_for :header_tags do
+  = javascript_pack_tag 'admin', async: true, crossorigin: 'anonymous'
+
+- content_for :page_title do
+  = t('admin.settings.about.title')
+
+- content_for :heading do
+  %h2= t('admin.settings.title')
+  = render partial: 'admin/settings/shared/links'
+
+= simple_form_for @admin_settings, url: admin_settings_about_path, html: { method: :patch } do |f|
+  = render 'shared/error_messages', object: @admin_settings
+
+  %p.lead= t('admin.settings.about.preamble')
+
+  .fields-group
+    = f.input :site_extended_description, wrapper: :with_block_label, as: :text, input_html: { rows: 8 }
+
+    %p.hint
+      = t 'admin.settings.about.rules_hint'
+      = link_to t('admin.settings.about.manage_rules'), admin_rules_path
+
+  .fields-row
+    .fields-row__column.fields-row__column-6.fields-group
+      = f.input :show_domain_blocks, wrapper: :with_label, collection: %i(disabled users all), label_method: lambda { |value| t("admin.settings.domain_blocks.#{value}") }, include_blank: false, collection_wrapper_tag: 'ul', item_wrapper_tag: 'li'
+    .fields-row__column.fields-row__column-6.fields-group
+      = f.input :show_domain_blocks_rationale, wrapper: :with_label, collection: %i(disabled users all), label_method: lambda { |value| t("admin.settings.domain_blocks.#{value}") }, include_blank: false, collection_wrapper_tag: 'ul', item_wrapper_tag: 'li'
+
+  .fields-group
+    = f.input :site_terms, wrapper: :with_block_label, as: :text, input_html: { rows: 8 }
+
+  .actions
+    = f.button :button, t('generic.save_changes'), type: :submit