KAFKA-7223: Suppress API with only immediate emit

[vvcephei]

Part 1 of the suppression API.

• add the DSL suppress method and config objects
• add the processor, but only in "identity" mode
  (i.e., it will forward only if the suppression spec says to forward immediately)
• add tests

Committer Checklist (excluded from commit message)

• Verify design and implementation
• Verify test coverage and CI build status
• Verify documentation (including upgrade notes)