Fixes https://github.com/spring-projects/spring-integration/issues/3038 * Add more delegating setters into the `AbstractRemoteFileOutboundGateway` for its `RemoteFileTemplate` property * Restrict externally provided `RemoteFileTemplate` from modifications in the `AbstractRemoteFileOutboundGateway`: those options must be configured on that external `RemoteFileTemplate` * Expose new options in the Java DSL specs