Reorganize macros into separate component files

Replace a few old UI Module instances with  macros

templates/components/sidenav_item.html

@@ -0,0 +1,28 @@
+{% from "components/icon.html" import Icon %}
+
+{% macro SidenavItem(label, href, active=False, icon=None, subnav=None) -%}
+  <li>
+  <a class="sidenav__link {% if active %}sidenav__link--active{% endif %}" href="{{href}}" title="{{label}}">
+    {% if icon %}
+      {{ Icon(icon, classes="sidenav__link-icon") }}
+    {% endif %}
+
+    <span class="sidenav__link-label">{{label}}</span>
+  </a>
+
+  {% if subnav and active %}
+      <ul>
+      {% for item in subnav %}
+      <li>
+          <a class="sidenav__link {% if item["active"] %}sidenav__link--active{% endif %}" href="{{item["href"]}}" title="{{item["label"]}}">
+          {% if "icon" in item %}
+              {{ Icon(item["icon"], classes="sidenav__link-icon") }}
+          {% endif %}
+          <span class="sidenav__link-label">{{item["label"]}}</span>
+          </a>
+      </li>
+      {% endfor %}
+      </ul>
+  {% endif %}
+  </li>
+{%- endmacro %}