ui: hide DText "Formatting help" link in dialog boxes.

Hide the "Formatting help" link for single-line DText fields in dialog boxes, such as after the
"Reason" field in the flag, appeal, and report dialog boxes.

app/logical/dtext_input.rb

@@ -18,7 +18,7 @@ class DtextInput < SimpleForm::Inputs::Base
     t = template
     merged_input_options = merge_wrapper_options(input_html_options, wrapper_options)
 
-    t.tag.div(class: "dtext-previewable", spellcheck: true) do
+    t.tag.div(class: ["dtext-previewable", ("dtext-inline" if options[:inline])], spellcheck: true) do
       if options[:inline]
         t.concat @builder.text_field(attribute_name, merged_input_options)
       else