Provide hateoas discoverabilty of actuator endpoints without spring-hateoas

[philwebb]

It would be nice if the current /actuator endpoint worked even if spring-hateoas isn't in use. Particularly if systems are in place that want to know what endpoints are available without hitting each one individually.

[philwebb]

Related to #6886 which would be the obvious place to put this endpoint.

[mbhave]

Done as part of #7108. The CloudFoundryDiscoveryEndpoint returns a HAL response for the Cloud Foundry actuators even when spring-hateoas is not in use.

[philwebb]

I think we only did this for the CloudFoundryDiscoveryEndpoint, we should consider if we want it also for the regular actuators endpoint.

[mbhave]

Good point. I suppose we can add support for this in the HalJsonMvcEndpoint. The HalBrowserMvcEndpoint, I think, would still require spring-hateoas.