feat: add extraSecrets support to trustee overrides

Enable custom secret mounting in KBS via extraSecrets array.
Loaded via extraValueFiles mechanism across all profiles.

Author: butler54

overrides/values-trustee.yaml

@@ -10,4 +10,6 @@ kbs:
     - name: "kbsres1"
       key: "secret/data/hub/kbsres1"
     - name: "passphrase"
-      key: "secret/data/hub/passphrase"
+      key: "secret/data/hub/passphrase"
+  extraSecrets:
+    - mySecret