Describe the change
This PR ports changes that @phutelmyer made in order to remove WeasyPrint from Strelka. From the original PR:

This PR removes WeasyPrint and its associated functionalities from the ScanEmail class for security reasons. Previously, WeasyPrint was used for generating thumbnails from HTML content in emails. This functionality involved making external network requests, which posed potential security risks. By removing WeasyPrint, we eliminate these risks and ensure that our email processing does not inadvertently leak data or fetch resources from untrusted sources.

The changes in this PR include:

• Removal of WeasyPrint:
  • All instances of WeasyPrint and related code have been removed from the ScanEmail class.
• Removal of Thumbnail Generation:
  • The thumbnail generation feature has been entirely removed. This includes methods and code that handled the creation and embedding of thumbnails in the email scan results.

Describe testing procedures
Test referencing WeasyPrint was removed and base functionality tested with local build fo Strelka.

Sample output
N/A

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of and tested my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings