* Introduce RSocketInteractionModel
* Deprecate `RSocketOutboundGateway.Command` in favor of newly introduced
top level `RSocketInteractionModel`
* Deprecate setter, DSL and XML configurations for the deprecated
`RSocketOutboundGateway.Command` in favor of newly introduced configurators
for the mentioned `RSocketInteractionModel`
* Add `IntegrationRSocketEndpoint.getInteractionModels()` contract for
inbound endpoints.
This way we can restrict mapped endpoints to the particular interaction
model(s)
* Add DSL and XML configuration for inbound interaction model option
* Document changes
* * Rebased into master; fix conflicts
* Fix consistency for `RetrieveSpec` in the `RSocketOutboundGateway`
and `rsocket.adoc`
* * Fix language in JavaDos and XSD attributes
42b812b711