bugfix/sign-check-validation: Added changes for validating both cat and sys files for signatures

[Rohit Mishra (rohimish-qc)]

Description

Added changes for validating both cat and sys files for signatures

Fixes #

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Hotfix (urgent fix targeted at a release/x.y branch)
• Refactor (no functional change)
• Performance improvement
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Test-only change
• CI / build-pipeline change

How has this been tested?

The script ran on the generated attested files, it validated the signatures of the sys and cat files.

Case 1: When signatures were not valid

Case 2: When signatures were valid

Checklist

• All required CI checks are green on the latest commit of this PR
• Build succeeds following the steps in the README / src/linux/README.md
• My code follows the Code Style Guidelines of this project
• My branch follows the naming convention: <branch-prefix>/<area>/<description>
• PR title follows the Conventional Commits format with our full-word types (feature / bugfix / hotfix / docs)
• I have performed a self-review of my own code
• I have added code comments in areas that are complex or hard to understand
• My changes generate no new compiler warnings
• I have added tests for my fix or feature (or noted why tests are not feasible)
• New and existing tests pass locally with my changes
• My branch is rebased onto the latest develop (or release/x.y for hotfix) - no merge commits
• Every commit has Signed-off-by: (DCO) - see CONTRIBUTING.md
• I have linked the relevant issue if any (Fixes #...)
• Any dependent changes have been merged and published in downstream modules