User files is disclosed when someone called while the screen is locked

## Summary: User files in the server is disclosed while the screen is locked when someone called. ## Steps To Reproduce: [add details for how we can reproduce the issue] 1.) Make 2 Accounts, Lets call them Account A and Account B 2.) Using Account A login to (https://nextcloud/apps/spreed/) 3.) Using Account B login to NextCloud Talk App in your Phone and Lock the Screen 4.) Using Account A call Account B 5.) Using Account B accept the call and click the Message or SMS icon in the bottom left 6.) Attach a file and Press share from your nextcloud server 7.) You can see the user files ## Supporting Material/References: [list any additional material (e.g. screenshots, logs, etc.)] ████ ## Impact A malicious attacker can see the user files by calling the phone while the screen is locked.