What would you like to be added:

Plugin dnstap should support configuration options for allowed types of DNSTAP messages.
The config may look like

  dnstap tcp://127.0.0.1:9123 full CR FR

where all parameters after endpoint are optional
or

  dnstap tcp://127.0.0.1:9123 full {
    allow CR FR
  }

Other plugins should be able to check these config options. Bunch of booleans is ok.
See also #4179 (comment) for reference

Why is this needed:
PR #4179 removed the ability to disable CQ and/or CR messages with flags passes via context.
Adding the configuration options to dnstap plugin will restore ability to control generation of dnstap messages of particular types.

Note, other popular DNS servers (e.g. unbound) also have similar configuration options.