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/project-static/styles/transitional/_tables.scss

@@ -23,7 +23,6 @@ table.attr-table {
 
   // Restyle row header
   th {
-    color: $gray-700;
     font-weight: normal;
     width: min-content;
   }