Throttle dblog entries

Issue #2932073 on drupal.org by drupatz.

According to the change to data protection ordinance in May 2018, a possibility of throttling the logging of sensitive remote instance data should be given.

There should be 2 Options:

1. Default DRD logging behavior.
2. DRD logging with metadata but without the response data (message/variables of watchdog-table).
- This one is kind of sensitive, because eg actions like collect information and projects status need to be saved to db to keep DRD alive.
- Thinking about that, it shouldn't be possible to skip logging for certain actions. Therefore it should be a method, that provides the possibility to skip loggin for 'some' actions, that are previously determined by configuration.

A checkbox should define, which option gets processed. If checked, #2 (closed) happens, but the response data gets stored temporarily (not in db) inside a cookie (to view the data, an additional tab 'Outputs' should be created, where only cookie data gets rendered.). Otherwise normal default behavior.
That checkbox should be settable globally (all actions on all hosts) and per action.
I've already begun with the implementation of that and will soon post a patch and documentation.