Accept evidence handling structures null entries

[sarroutbi]

Update ImaLog and UefiLog structures to handle null entries field:

• Change entries field from String to Option in both structures
• Update serialization/deserialization logic to handle null values
• Modify entry count calculation for ImaLog to handle None entries
• Add comprehensive tests for null entries scenarios
• Update context_info.rs to wrap entries in Some() when creating evidence

This change improves robustness when handling evidence data that may null entry fields, which can occur in certain attestation scenarios.

[sarroutbi]

/packit retest-failed

[codecov]

Codecov Report

❌ Patch coverage is 91.30435% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 58.10%. Comparing base (fb4bcdc) to head (ad357df).
⚠️ Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
keylime/src/structures/evidence_handling.rs	90.47%	2 Missing ⚠️

Additional details and impacted files

Flag	Coverage Δ
e2e-testsuite	58.10% <91.30%> (+0.07%)	⬆️
upstream-unit-tests	58.10% <91.30%> (+0.07%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
keylime/src/context_info.rs	53.71% <100.00%> (ø)
keylime/src/structures/evidence_handling.rs	63.50% <90.47%> (+6.25%)	⬆️

... and 7 files with indirect coverage changes

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[sarroutbi]

/packit retest-failed

[ansasaki]

LGTM!