feat(testing): add JUnitFormatter for deterministic XML test reports

[murad-1999]

📋 Summary

This PR introduces the JUnitFormatter to the mofa-testing crate, enabling the deterministic generation of Ant/Surefire compliant JUnit XML test reports.

🔗 Related Issues

Closes #

Related to #
Issue #1567

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🧠 Context

• Added JUnitFormatter: Implements the ReportFormatter trait to generate <testsuite>, <testcase>, <failure>, and <skipped/> XML tags natively.
• Zero Bloat: Achieved the implementation entirely through a manual, highly-efficient string builder without adding heavy XML serialization dependencies to Cargo.toml.
• Security First (XML Escaping): Added a robust escape_xml utility that safely encodes <, >, &, ", and '. It also intercepts and strips invalid raw control characters and handles chaotic inputs (CDATA, emojis, null bytes) to prevent strict XML parsers from crashing.
• CI Determinism: Ensures flake-free CI by enforcing a strict sequential iteration order and explicitly formatting all floats (durations) to exactly 3 decimal places ({:.3}).
• Memory Efficiency: Implemented payload truncation on the <failure message="..."> attribute to prevent massive memory allocations and redundant XML bloat when handling massive stack traces.
• Exports: Exposed the formatter correctly at tests/src/report/mod.rs and tests/src/lib.rs

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🛠️ Changes

tests/src/lib.rs (Added public export)
tests/src/report/mod.rs (Added module export)
tests/src/report/format.rs (Core implementation, escape_xml logic, and unit tests)-->

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🧪 How you Tested

Added comprehensive, strict string-literal snapshot tests covering:

• test_all_passing: Validates a clean test run.
• test_mixed_status: Validates failures and skips mapping to <failure> and <skipped/>.
• test_case_with_error_payload: Validates basic XML character escaping.
• test_case_with_metadata: Validates structure when metadata is present.
• test_chaotic_escaping: Stress tests the escaping utility against null bytes, emojis, and deeply nested quotes.

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📸 Screenshots / Logs (if applicable)

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⚠️ Breaking Changes

• No breaking changes
• Breaking change (describe below)

If breaking:

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🧹 Checklist

Code Quality

• Code follows Rust idioms and project conventions
• cargo fmt run
• cargo clippy passes without warnings

Testing

• Tests added/updated
• cargo test passes locally without any error

Documentation

• Public APIs documented
• README / docs updated (if needed)

PR Hygiene

• PR is small and focused (one logical change)
• Branch is up to date with main
• No unrelated commits
• [ x] Commit messages explain why, not only what

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🚀 Deployment Notes (if applicable)

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🧩 Additional Notes for Reviewers