Use HTML beautifier to indent ERB files

We had inconsistent indentation in many places. Now we're fixing them
and adding a linter to our CI so we don't accidentally introduce
inconsistent indentations again.

app/components/attachable/fields_component.html.erb

@@ -24,7 +24,9 @@
   </div>
 
   <div class="small-12 column">
-    <div class="progress-bar-placeholder"><div class="loading-bar"></div></div>
+    <div class="progress-bar-placeholder">
+      <div class="loading-bar"></div>
+    </div>
   </div>
 
   <hr>