feat: extends plausible analytics to support self hosted installations (#4824)

server/modules/analytics/plausible/code.yml

 head: |
-  <script defer data-domain="{{domain}}" src="https://plausible.io/js/plausible.js"></script>
+  <script defer data-domain="{{domain}}" src="{{plausibleJsSrc}}"></script>

server/modules/analytics/plausible/definition.yml

@@ -11,3 +11,9 @@ props:
     title: Domain
     hint: The value of the data-domain property
     order: 1
+  plausibleJsSrc:
+    type: String
+    default: https://plausible.io/js/plausible.js
+    title: Plausible JS Script source
+    hint: The URL of Plausbile Script (only needed when using a self hosted installation)
+    order: 2