workloads: Migrate Kafka source, tests and profile to open source

[AlexWFMS]

Summary

Migrate the Kafka workload into the public Virtual Client projects while preserving
the existing command, profile, exception, warmup, concurrency, and telemetry behavior.

• Add base/client/server executors and producer/consumer parsers.
• Migrate unit tests, functional tests, output examples, and PERF-KAFKA.json.
• Add dependency-installation coverage for all four advertised platforms and
  direct profile-schema validation.
• Add workload/profile documentation describing actual metric capture, parameters,
  fixed ports, topology limitations, Windows scripts, and troubleshooting.

Validation

Check	Result
Original Kafka unit tests	29 passed
Original Kafka functional tests	19 passed
Public Kafka unit tests	29 passed
Public Kafka functional tests	24 passed
Direct Kafka profile schema validation	Included in passing functional tests
Production project and normal analyzers	Passed
Patch whitespace	Passed
Claude Opus 5.5 implementation critique	No runtime/test-parity regressions found; documentation findings corrected
Website build	Blocked: dependency restore failed (proxy 404 and TLS handshake failure)
Live old/new parity	Not run

Tests use the existing in-memory fixtures; platform test cases are not evidence of
live ARM64/Windows/Linux parity.

Draft / release blockers

This PR is not ready to merge:

• The exact kafka_2.13-3.8.0-2.zip archive is not yet in the public package store.
  Resolve the modified Windows scripts' redistribution/notice question before
  copying the archive. Do not silently substitute a different archive.
• The JDK archive is already public with matching name, byte length, MD5, and
  content type; all four platform binaries were verified.
• Complete the website build when dependency access is available.
• Select a unique next public patch version and update VERSION; package-version
  lookup was blocked by TLS failures. No prerelease packages have been published.
• Complete live A/B parity for linux-x64, linux-arm64, win-x64, and win-arm64,
  in both single-system and client/server topologies.
• Obtain coworker verification and explicit owner direction before merging.

Coordinated rollout

Merge the validated public change first, then publish all four runtime packages
and the Framework/TestFramework prereleases from merged code. Only after remote
package availability is verified should the paired internal cleanup update all
six pins, remove duplicate implementation/profile/documentation, and validate
its assembled artifacts. No internal removal or merge has occurred.

Intentional behavior preservation

Producer output has a parser, but the current executor emits benchmark metrics
only for consumer commands. This migration does not enable producer telemetry,
rename metrics, harden parsing, upgrade Kafka, or repair inherited runtime behavior.

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