fix(#1472): include project id in plan and apply headers

[Mallikarjunadevops]

🧠 Ai UsageDetails (if applicable):

What Resolves #1472.

Digger's PR reporting currently outputs generic headers like "Apply output" or "Plan output," which becomes extremely difficult to parse for users operating within Monorepos mapping to multiple projects.
This Pull Request addresses the issue by injecting the projectId dynamically into both reportTerraformApplyOutput and reportTerraformPlanOutput so that each collapsible comment clearly identifies its target project (e.g., "Apply output for my-project").

How

• Updated libs/execution/execution.go to explicitly include the projectId in the Apply output comment strings.
• Updated cli/pkg/digger/digger.go to explicitly include the projectId in the Plan output comment strings.
• Preserved existing markdown formatting by **bolding** the injected project IDs when the platform supports it.

Testing

• Relies on automated CI test suites to verify string comparisons and backwards compatibility.

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Disclosure: I consulted with an AI assistant while writing this code and reviewed and verified manually