Fixes https://github.com/spring-projects/spring-integration/issues/8705
an internal `MethodInvocationGateway` is a `MessagingGatewaySupport`
extension with all the logic available there.
One of the option introduced in `5.2.2` to be able to throw a `MessageTimeoutException`
instead of returning `null` when no reply received in time from downstream flow
* Expose an `errorOnTimeout` on the `@MessagingGateway` and `GatewayEndpointSpec`
* Propagate this option from a `GatewayProxyFactoryBean` down to its internal
`MethodInvocationGateway` implementation
* Modify couple tests to react for `errorOnTimeout` set to `true`
* Document the feature
Fix language in Docs
Co-authored-by: Gary Russell <grussell@vmware.com>