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/utilities/templates/form_helpers/render_field.html

@@ -36,7 +36,7 @@
     {% elif 'data-clipboard' in field.field.widget.attrs %}
       <div class="input-group">
         {{ field }}
-        <button type="button" title="{% trans "Copy to clipboard" %}" class="btn btn-outline-dark copy-content" data-clipboard-target="#{{ field.id_for_label }}">
+        <button type="button" title="{% trans "Copy to clipboard" %}" class="btn copy-content" data-clipboard-target="#{{ field.id_for_label }}">
           <i class="mdi mdi-content-copy"></i>
         </button>
       </div>