This commit improves the configuration metadata annotation processor to
explicitly handle `@Endpoint` annotated class. Adding a new endpoint on
a project potentially creates the following keys:

* `endpoints.<id>.enabled`
* `endpoints.<id>.cache.time-to-live`
* `endpoints.<id>.jmx.enabled`
* `endpoints.<id>.web.enabled`

Default values are extracted from the annotation type. If an endpoint
is restricted to a given tech, properties from unrelated techs are not
generated.

Closes gh-9692