add-identity in filesystem-realm with no notification

In domain mode only, host -> server -> security -> security realms -> filesystem realm, add an identitty with attributes, the operation doesn't return success or error.

After investigation it turns out there is a bug WFCORE-3876 on filesystem-realm add-identity and add-identity-attribute, it blocks the operation and other operations. Instead to run the write operations as composite, use the Flow Task api.