Change log for MIMECAST_MAIL

Date Changes
2023-03-31 Enhancement-
- Mapped "filename_for_malachite" to "principal.resource.name".
- Mapped "fileName" to "principal.process.file.full_path".
- Mapped "sha256" to "target.file.sha256".
- Mapped "sha1" to "target.file.sha1".
- Added conditional check for "aCode".