[BUG] The file extension is missing when save file on Windows Desktop App

Description:

When downloading a file from a chat on a Windows client, the file extension is not added. (see screenshot)
For example:
People 1 send to chat file "document.pdf"
on chat we have "document.pdf"
People 2 try to download this document via desktop app "Save as" - rename to "document 01.01.2022" and extensions change from pdf to .2022 and we have file no PDF "document 01.01.2022". Same problem on two machine with Windows 10, on MacOS is OK.

Steps to reproduce:

1. People 1 send to chat file "document.pdf"
2. On chat we have "document.pdf" OK
3. People 2 try to download this document via desktop app Windows client "Save as" - with new name "document 01.01.2022" and result file without .pdf extension.

Expected behavior:

Save file with extension.
For ex: Send file.pdf -> save file with new name "document 01.0.2022" -> document 01.0.2022

Actual behavior:
Send file.pdf -> Save -> file with new name "name 01.01.2022"
.pdf missing.

Server Setup Information:

• Version of Rocket.Chat Server: 5.3.0
• Operating System: Docker on Synology DSM 6.2
• Deployment Method: Docker compose
• Number of Running Instances: 1
• DB Replicaset Oplog: wiredTiger Oplog ON
• NodeJS Version: v14.19.3
• MongoDB Version: 5.0.13 / wiredTiger

Client Setup Information

• Desktop App or Browser Version: Desktop App 3.8.12
• Operating System: Windows 10

Start by reproducing the Save as flow in the Windows desktop app using a file such as document.pdf and a renamed filename containing periods. Trace the desktop download and save handling; done means the original .pdf extension is preserved when the user chooses a new name, while the existing macOS behavior remains unaffected.