Deploy on BTP (#793)

minimal changes required to deploy the CAP samples in _shared db_ mode:
- db: all bookshop, orders, reviews CDS models into one db instance (_shared-db_)
- services: bookstore, orders, reviews
- approuter with UI symlinks:
  - Vue: bookshop, reviews
  - Fiori: orders
 - authentification: xsuaa
 - messaging: Event Mesh
 - destinations: orders, reviews
- cds:
  - projection OrdersNoDraft for backend direct access
  - event OrderChanged
- deployment: mta.yml

event-mesh.json

@@ -0,0 +1,29 @@
+{
+  "version": "1.1.0",
+  "options": {
+    "management": true,
+    "messagingrest": true,
+    "messaging": true
+  },
+  "rules": {
+    "topicRules": {
+      "publishFilter": [
+        "*"
+      ],
+      "subscribeFilter": [
+        "*"
+      ]
+    },
+    "queueRules": {
+      "publishFilter": [
+        "*"
+      ],
+      "subscribeFilter": [
+        "*"
+      ]
+    }
+  },
+  "authorities": [
+    "$ACCEPT_GRANTED_AUTHORITIES"
+  ]
+}