Major overhaul

- Docker buildx support in CI
- Cypress API Testing in CI
- Restructured folder layout (insert clean face meme)
- Added Swagger documentation and validate API against that (to be completed)
- Use common base image for all supported archs, which includes updated nginx with ipv6 support
- Updated certbot and changes required for it
- Large amount of Hosts names will wrap in UI
- Updated packages for frontend
- Version bump 2.1.0

frontend/js/app/error/main.ejs

@@ -0,0 +1,7 @@
+<i class="fe fe-alert-triangle mr-2" aria-hidden="true"></i>
+<%= code ? '<strong>' + code + '</strong> &mdash; ' : '' %>
+<%- message %>
+
+<% if (retry) { %>
+    <br><br><a href="#" class="btn btn-sm btn-warning retry"><%- i18n('str', 'try-again') %></a>
+<% } %>

frontend/js/app/error/main.js

@@ -0,0 +1,27 @@
+const Mn       = require('backbone.marionette');
+const template = require('./main.ejs');
+
+module.exports = Mn.View.extend({
+    template:  template,
+    className: 'alert alert-icon alert-warning m-5',
+
+    ui: {
+        retry: 'a.retry'
+    },
+
+    events: {
+        'click @ui.retry': function (e) {
+            e.preventDefault();
+            this.getOption('retry')();
+        }
+    },
+
+    templateContext: function () {
+        return {
+            message: this.getOption('message'),
+            code:    this.getOption('code'),
+            retry:   typeof this.getOption('retry') === 'function'
+        };
+    }
+
+});