Rename submit_form component to page_footer

Submit form was
- a confusing name in itself
- not descriptive, because it also has an optional ‘back’ link

This commit also puts this component in as many pages as possible, stripping
out any hard-coded buttons and links.

It replaces any usage of buttons for ‘back’, because these are links, not
buttons (ie they don’t change any data).

app/templates/components/page-footer.html

@@ -0,0 +1,11 @@
+{% macro page_footer(button_text=None, back_link=False, back_link_text="Back", destructive=False) %}
+  <div class="page-footer">
+    {% if button_text %}
+      <input type="hidden" name="csrf_token" value="{{ csrf_token() }}" />
+      <input type="submit" class="button{% if destructive %}-destructive{% endif %}" value="{{ button_text }}" />
+    {% endif %}
+    {% if back_link %}
+      <a class="page-footer-back-link" role="button" href="{{ back_link }}">{{ back_link_text }}</a>
+    {% endif %}
+  </div>
+{% endmacro %}

app/templates/components/submit-form.html

@@ -1,9 +0,0 @@
-{% macro submit_form(button_text, back_link=False, back_link_text="Back", destructive=False) %}
-  <div class="submit-form">
-    <input type="hidden" name="csrf_token" value="{{ csrf_token() }}" />
-    <input type="submit" class="button{% if destructive %}-destructive{% endif %}" value="{{ button_text }}" />
-    {% if back_link %}
-      <a class="submit-form-back-link" role="button" href="{{ back_link }}">{{ back_link_text }}</a>
-    {% endif %}
-  </div>
-{% endmacro %}