This commit reworks the initial proposal so that jobs and triggers are
treated as first class concepts.

`/actuator/quartz` now returns the group names for jobs and triggers.

`actuator/quartz/jobs` returns the job names, keyed by the available
group names, while `/actuator/quartz/triggers` does the same for
triggers.

`/actuator/jobs/{groupName}` provides an overview of a job group. It
provides a map of job names with the class name of the job.
implementation

`/actuator/triggers/{groupName}` provides an overview of a trigger
group. There are five supported trigger implementations: cron, simple,
daily time interval, calendar interval, and custom for any other
implementation. Given that each implementation has specific settings,
triggers are split in five objects.

`/actuator/jobs/{groupName}/{jobName}` provides the full details of a
particular job. This includes a sanitized data map and a list of
triggers ordered by next fire time.

`/actuator/triggers/{groupName}/{triggerName}` provides the full details
of a particular trigger. This includes the state, its type, and a
dedicate object containing implementation-specific settings.

See gh-10364