feat(attachments): add XML and PFX file support (#14539)

Update frontend allowed file types and FileIcon mapping, and backend
Attachment constants to accept .xml and .pfx files

# Pull Request Template

## Description
Customer also wanted XML support along with .pfx

Following up on #14456

## Type of change

- [x] New feature (non-breaking change which adds functionality)

## How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Provide
instructions so we can reproduce. Please also list any relevant details
for your test configuration.
locally

<img width="864" height="512" alt="CleanShot 2026-05-22 at 11 43 20@2x"
src="https://github.com/user-attachments/assets/4cbf65d4-b919-4a4b-bf75-a4f2e8690586"
/>

<img width="870" height="1440" alt="CleanShot 2026-05-22 at 11 44 03@2x"
src="https://github.com/user-attachments/assets/e763b49d-4365-4c45-9b43-b0c39af87656"
/>


## Checklist:

- [x] My code follows the style guidelines of this project
- [x] I have performed a self-review of my code
- [x] I have commented on my code, particularly in hard-to-understand
areas
- [ ] I have made corresponding changes to the documentation
- [x] My changes generate no new warnings
- [x] I have added tests that prove my fix is effective or that my
feature works
- [x] New and existing unit tests pass locally with my changes
- [x] Any dependent changes have been merged and published in downstream
modules

app/javascript/shared/constants/messages.js

@@ -39,12 +39,14 @@ export const ALLOWED_FILE_TYPES =
   'audio/*,' +
   'video/*,' +
   '.3gpp,' +
+  '.xls, .xlsx, .xml, .pfx,' +
   'text/csv, text/plain, application/json, application/pdf, text/rtf,' +
   'application/xml, text/xml,' +
   'application/zip, application/x-7z-compressed application/vnd.rar application/x-tar,' +
   'application/msword, application/vnd.ms-excel, application/vnd.ms-powerpoint, application/vnd.oasis.opendocument.text,' +
   'application/vnd.openxmlformats-officedocument.presentationml.presentation, application/vnd.openxmlformats-officedocument.spreadsheetml.sheet,' +
-  'application/vnd.openxmlformats-officedocument.wordprocessingml.document,';
+  'application/vnd.openxmlformats-officedocument.wordprocessingml.document,' +
+  'application/x-pkcs12, application/pkcs12,';
 
 export const CSAT_RATINGS = [
   {