Closes #14871: Complete work on UI cleanup (#15341)

* Fix left padding of login button in top menu

* Relocate "add" buttons for embedded object tables

* Remove unused data template block & getNetboxData() utility function

* Remove bottom margin from last <p> element in rendered Markdown inside a table cell

* Prevent TomSelect from initializing on <select> elements with a size

* Fix styling of dropdown menu button for circuit commit rate

* Change .color-block to display: inline-block

* Delete unused static asset

* Improve contrast between menu group headings & items

* Remove custom color for attr-table row headings

* Fix border color of copy-to-clipboard button

* Fix toast text color in dark mode

* Fix rack elevation label/image toggles

* Increase border radius for small buttons

* Fix object selector

netbox/templates/base/base.html

@@ -70,10 +70,5 @@
     {# User messages #}
     {% include 'inc/messages.html' %}
 
-    {# Data container #}
-    <div id="netbox-data" style="display: none!important; visibility: hidden!important">
-      {% block data %}{% endblock %}
-    </div>
-
   </body>
 </html>