Preserve GitHub expression operators in safe-output JSON (#56653)

* Initial plan

* Preserve safe-output expression operators

Co-authored-by: pelikhan <4175913+pelikhan@users.noreply.github.com>

* Triage PR for merge readiness

Co-authored-by: pelikhan <4175913+pelikhan@users.noreply.github.com>

* Preserve templatable expression operators

Co-authored-by: pelikhan <4175913+pelikhan@users.noreply.github.com>

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Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: pelikhan <4175913+pelikhan@users.noreply.github.com>