Reorganize test execution from language-by-language to test-by-test with matrix output

[Copilot]

• Analyze current test execution structure
• Understand issue requirements: tests should run test-by-test with each language instead of language-by-language
• Refactor run_tests.py to execute tests by test type (basic_types, arrays, serialization) across all languages
• Create test result matrix display showing pass/fail per language per test
• Reduce repetitive output by consolidating similar messages
• Further reduce repetitive information in cross-platform tests
• Test with verbose mode to ensure it still works correctly
• Update documentation to reflect new test execution structure
• Address code review comments: use constants and add helpful notes
• Simplify summary to remove repetition (just show pass count, not all details again)
• Clarify test section names with descriptive explanations

Original prompt

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This section details on the original issue you should resolve

<issue_title>Further test improvements. </issue_title>
<issue_description>Tests are currently being run language by language.
Instead they should be run test by test with each language.

After the tests are run a test matrix can be output showing if the tests passed per language.

Currently there is still a lot of repeated information when you run the test all script.

The information should be reduced so there is no repetition.</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Further test improvements.  #21

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[rijesha]

@copilot the output summary results is still too large and mostly just repeated. I think it can be whittled down a lot more.

It is also a bit confusing as to what:
CROSS-LANGUAGE COMPATIBILITY is and what CROSS-PLATFORM PIPE TESTS are.

[Copilot]

@copilot the output summary results is still too large and mostly just repeated. I think it can be whittled down a lot more.

It is also a bit confusing as to what:
...

Simplified the summary to show just the overall pass count instead of repeating all individual test results. Also clarified the test section names:

• "CROSS-LANGUAGE COMPATIBILITY" → "CROSS-LANGUAGE DATA INTERCHANGE" with description
• "CROSS-PLATFORM PIPE TESTS" → "STDIN/STDOUT STREAMING TESTS" with description

The summary went from ~50 lines to just 3 lines showing the overall result.

Before:

📊 TEST RESULTS SUMMARY
🔧 Code Generation:
      C: ✅ PASS
     TS: ✅ PASS
     PY: ✅ PASS
    CPP: ✅ PASS
🔨 Compilation:
      C: ✅ PASS
     TS: ❌ FAIL
    CPP: ✅ PASS
[... repeated for all test types ...]
📈 Overall Results: 20/21 tests passed
🎉 SUCCESS: 95.2% pass rate

After:

📊 TEST RESULTS SUMMARY
📈 20/21 tests passed
🎉 SUCCESS: 95.2% pass rate

Changes in commit a39227a.