Reorganize macros into separate component files

Replace a few old UI Module instances with  macros

templates/components/empty_state.html

@@ -0,0 +1,13 @@
+{% from "components/icon.html" import Icon %}
+
+{% macro EmptyState(message, actionLabel, actionHref, icon=None) -%}
+  <div class='empty-state'>
+    <p>{{ message }}</p>
+
+    {% if icon %}
+      {{ Icon(icon) }}
+    {% endif %}
+
+    <a href='{{ actionHref }}' class='usa-button usa-button-big'>{{ actionLabel }}</a>
+  </div>
+{%- endmacro %}