Rename module

HighlightTags was bad because:
- we haven’t called placeholders ‘tags’ for a long time
- it also does resizing of the `<textarea>`, not just highlighting the
  placeholders

app/templates/components/textbox.html

@@ -2,7 +2,7 @@
   field,
   label=None,
   hint=False,
-  highlight_tags=False,
+  highlight_placeholders=False,
   autofocus=False,
   autosize=False,
   colour_preview=False,
@@ -35,7 +35,7 @@
       {% endif %}
     </label>
     {%
-      if highlight_tags
+      if highlight_placeholders or autosize
     %}
       {% set field_class = 'form-control-{} textbox-highlight-textbox'.format(width) %}
     {% else %}
@@ -48,8 +48,8 @@
     %}
     {{ field(
       class=field_class,
-      data_module='highlight-tags' if highlight_tags or autosize else '',
-      data_highlight_placeholders='true' if highlight_tags else 'false',
+      data_module='enhanced-textbox' if highlight_placeholders or autosize else '',
+      data_highlight_placeholders='true' if highlight_placeholders else 'false',
       rows=rows|string,
       **kwargs
     ) }}