[Minor] Add additional bad attachment types

[Minor] Add additional bad attachment types

- app: Executable Application, blocked in Outlook by default
- aspx: Active Server Page Extended, blocked in Outlook by default
- dll: Dynamic-link Library
- dqy: Microsoft Query File, blocking recommended in MS365
- iqy: ditto
- mht: MHTML File, often abused for phishing and exploit attempts
- mhtml: ditto
- oqy: Microsoft Query File, blocking recommended in MS365
- rqy: ditto
- slk: Microsoft Symbolic Link
- wim: Windows Imaging Format