Add SwiftHashPrefix parameter

Adds a new parameter 'SwiftHashPrefix' to allow swift
to have its hash_prefix parameter set.

Change-Id: If46a83e5f476ab8ed553b67b624c780a21ee50a5
Story: 2008411
Related-RHBZ: #1903901

deployment/swift/swift-base.yaml

@@ -35,6 +35,12 @@ parameters:
       in the ring.
     hidden: true
     type: string
+  SwiftHashPrefix:
+    default: ''
+    description: A random string to be used as an extra salt when hashing to determine mappings
+      in the ring.
+    hidden: true
+    type: string
 
 outputs:
   role_data:
@@ -43,3 +49,4 @@ outputs:
       service_name: swift_base
       config_settings:
         swift::swift_hash_path_suffix: {get_param: SwiftHashSuffix}
+        swift::swift_hash_path_prefix: {get_param: SwiftHashPrefix}

releasenotes/notes/swift_hash_path_prefix-5ecc32ed5d78158b.yaml

@@ -0,0 +1,6 @@
+---
+features:
+  - |
+    The SwiftHashPrefix parameter allows the operator to set
+    Swift swift_hash_path_prefix using a Heat parameter in their
+    Templates.