feat: embed all the images in header/footer as base64 data

[grigoriev]

to fix resolving of possible non-accessible host from weasyprint service

Refs: #112

Proposed changes

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Checklist

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• [ ] I have read the CONTRIBUTING document
• [ ] If applicable, I have added tests that prove my fix is effective or that my feature works
• [ ] If applicable, I have checked that any relevant tests pass after adding my changes
• [ ] I have updated any relevant documentation

[sonarcloud[bot]]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

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