feat(postgres): Failover postgres example maybe working!? Added FailoverTopology implementations for required capabilities, documented a bit, some more tests, and quite a few utility functions

examples/multisite_postgres/src/main.rs

@@ -0,0 +1,31 @@
+use harmony::{
+    inventory::Inventory,
+    modules::postgresql::{
+        K8sPostgreSQLScore, PublicPostgreSQLScore, capability::PostgreSQLConfig,
+    },
+    topology::{FailoverTopology, K8sAnywhereTopology},
+};
+
+#[tokio::main]
+async fn main() {
+    let postgres = PublicPostgreSQLScore {
+        postgres_score: K8sPostgreSQLScore {
+            config: PostgreSQLConfig {
+                cluster_name: "harmony-postgres-example".to_string(), // Override default name
+                namespace: "harmony-public-postgres".to_string(),
+                ..Default::default() // Use harmony defaults, they are based on CNPG's default values :
+                                     // "default" namespace, 1 instance, 1Gi storage
+            },
+        },
+        hostname: "postgrestest.sto1.nationtech.io".to_string(),
+    };
+
+    harmony_cli::run(
+        Inventory::autoload(),
+        FailoverTopology::<K8sAnywhereTopology>::from_env(),
+        vec![Box::new(postgres)],
+        None,
+    )
+    .await
+    .unwrap();
+}