feat: support deleting files in disk injects

[glattercj]

Supports adding a keyword to the src field of a file injection to delete the file/directory in a disk image. E.g.

      injections:
        - src: TERMINATED
          dst: /ProgramData/Microsoft/Windows Defender

Depends on sandia-minimega/minimega#1548

[activeshadow]

LGTM!

We'll need to update the minimega branches that get used in phenix to build the minimega image before merging this since the required minimega changes aren't merged in yet.

[glattercj]

@activeshadow Switched to using deletions array and delete files ... keyword in the minimega script template per matching updated minimega PR. Ex:

      deletions:
        - path: /foo/bar/baz.zip
        - path: /ProgramData/Microsoft/Windows Defender
          description: Remove (and disable) Windows Defender

Still depends on sandia-minimega/minimega#1548