Add button Attach file in Private Group

[alma06132]

Is your feature request related to a problem? Please describe.

• it is not possible to send file from TRIfA only from external app in Privet Group
• file send in direct message to offline contact is delivered when he come back to online, but in Private Group it is not delivered

Describe the solution you'd like
behavior similar to how it works in direct messages

Your system information:
TRIfA Version: [latest 1.0.228 30 March 2024]
App from F-Droid
Android OS Version: [Android 10, Android 14]
Device: Samsung Galaxy S9+ (Android 10) and Samsung Galaxy S22 Ultra (Android 14), both with latest official firmware

Describe alternatives you've considered
share file from another app (file manager)