Custom ransomware file extension

[mssalvatore]

Description

As a red team member, I want to be able to configure the file extension that the ransomware simulation uses to rename encrypted files, so that I can more accurately mimic specific ransomware threats.

Acceptance Criteria

• Encrypted files are renamed with a user-provided extension. (Default: ".m0nk3y")
  • Example: my_picture.jpg -> my_picture.jpg.m0nk3y
• None/empty is a valid extension. The ransomware payload will not rename files if no extension is provided.
• Any files that already have the user-provided extension are skipped.
• Ransomware configuration screen includes a field that allows the user to specify a file extension.
• Unit tests are written and provide comprehensive coverage.
• Documentation is written that describes how the file extensions are used.

[mssalvatore]

Resolved by #2206