[DPE-4066] HA interface (#317)

* Initial hacluster implementation

* Fix clustered check

* Check for relation in set_vip

* Hacluster test

* Fix test

* Add remove test

* Update libs

* Update client info on config change

* Cache vip in peer data

* Block on edge cases

* Bump coverage

* Blocking check

* Fix integration test

* App status with VIP

* Move vip to leader status

* Clear up vip caching

* Forgotten None

* Bump libs

config.yaml

@@ -16,6 +16,11 @@ options:
       The port on which the pgbouncer prometheus exporter serves metrics.
     type: int
 
+  vip:
+    description: |
+      Virtual IP to use to front pgbouncer units. Used only in case of external node connection.
+    type: string
+
   pool_mode:
     default: session
     description: |