templates: add missing center_update.html

Add html template for the route /action/center/update.
Finish the work started in commit 6ec26d16.

ogcp/templates/actions/center_update.html

@@ -0,0 +1,18 @@
+{% extends 'scopes.html' %}
+{% import "bootstrap/wtf.html" as wtf %}
+
+{% set sidebar_state = 'disabled' %}
+{% set btn_back = true %}
+
+{% block nav_folder %} active{% endblock %}
+{% block nav_folder_update %} active{% endblock %}
+{% block content %}
+
+<h1 class="m-5">{{_('Update center')}}</h1>
+
+{{ wtf.quick_form(form,
+                  method='post',
+                  button_map={'submit': 'primary'},
+                  extra_classes="mx-5") }}
+
+{% endblock %}