feat(DATAGO-121849): Document eval test instruction

[alimosaed]

What is the purpose of this change?

Running eval tests are confusing because there is no instruction or script for running eval tests.

How was this change implemented?

• Added evaluation/README.md with step-by-step instructions for running evaluation tests, environment variable requirements, and manual/automated setup options.

• Introduced new Makefile targets for evaluation tests (test-eval, test-eval-local, test-eval-workflow, test-eval-remote) and updated help text to document these options.

• Improved configuration setup in evaluation/run.py by ensuring the configs directory exists and automatically copying shared_config.yaml from examples if missing.

Key Design Decisions

How was this change tested?

• Manual testing: Ran the make test-eval and verified that the virtual environment is created and eval tests are executed.
• Unit tests
• Integration tests
• Known limitations

Is there anything the reviewers should focus on/be aware of?

• SAM should be completely setup with valid LLM keys and broker configs to run eval tests.
• SAM is not properly installed via uv package manager in the Make file. Therefore, we had to directly activate virtual environments via source command and run the sam application.

[sonarqube-solacecloud]

Quality Gate passed

Issues
0 New issues
0 Fixed issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
No data about Duplication

See analysis details on SonarQube