vhost: Allow setting proxy headers

roles/vhost/meta/argument_specs.yaml

@@ -103,6 +103,11 @@ argument_specs:
           - Only applicable if vhost_type is reverse_proxy and vhost_proxy_target_netproto is unix.
         type: str
         required: false
+      vhost_proxy_headers:
+        description: Dict of request headers and their values to set for proxied requests
+        type: dict
+        required: false
+        default: {}
       vhost_proxy_delete_headers:
         description: List of headers to delete from proxied requests
         type: list
@@ -229,6 +234,11 @@ argument_specs:
             type: str
             required: false
             default: "{{ vhost_proxy_target_socket if vhost_type == 'reverse_proxy' and vhost_proxy_target_netproto == 'unix' else '' }}"
+          proxy_headers:
+            description: Dict of request headers and their values to set for proxied requests
+            type: dict
+            required: false
+            default: "{{ vhost_proxy_headers }}"
           proxy_delete_headers:
             description: List of request headers to delete from proxied requests
             type: list