Fixes #6590 add set_remote_user parameter to synchronize

This allows usage of custom ssh configs for remote hosts where
the inventory user does not match the configured user.

library/files/synchronize

@@ -119,6 +119,12 @@ options:
       - Specify a --timeout for the rsync command in seconds. 
     default: 10 
     required: false
+  set_remote_user:
+    description:
+      - put user@ for the remote paths. If you have a custom ssh config to define the remote user for a host
+        that does not match the inventory user, you should set this parameter to "no".
+    default: yes
+    required: false
 notes:
    - Inspect the verbose output to validate the destination user/host/path
      are what was expected.
@@ -189,6 +195,7 @@ def main():
             times = dict(type='bool'),
             owner = dict(type='bool'),
             group = dict(type='bool'),
+            set_remote_user = dict(default='yes', type='bool'),
             rsync_timeout = dict(type='int', default=10)
         ),
         supports_check_mode = True