feat(test): add --output (text/json/yaml/github-actions) for machine-readable results

[Caesarsage]

Adds --output to microcks test, with four formats:

Value	Output
text (default)	Human-readable summary (unchanged default behaviour)
json	Full TestResult as JSON
yaml	Full TestResult as YAML
github-actions	GitHub Actions annotations + log groups + job step summary

Works for both the normal server path and --dry-run, since it's wired into the
shared test engine (runTestAndWait).

github-actions format

• ::group:: / ::endgroup:: log-folding per operation
• ::error:: per failing step, with the validation message
• ::error file=<spec>,line=<n>:: when the local spec is known (--dry-run --artifact),
  mapping the failing operation to its line so the annotation lands on the diff
• ::notice:: for passing operations, gated by MICROCKS_ACTIONS_VERBOSE
• A per-operation markdown table appended to $GITHUB_STEP_SUMMARY

Tests

• Unit tests for all four formatters, the github-actions escaping, the step
  summary, and the OpenAPI line-mapping (pkg/output).

Notes

• Supersedes feat: add global output formatter support (text/json/yaml) #371 (same --output, extended with github-actions + diff
  annotations) — that PR can be closed.
• A runnable end-to-end demo workflow lives on the https://github.com/Caesarsage/microcks-cli/actions/runs/28505381116
  Refs Feat: Microcks-CLI v2 - IDE (Vs code) Integration and Local Dev Loop Enhancement #255