Use non nullable context for PreviewMediaFragment

[JonasMayerDev]

PR by Alper

• [X] Tests written, or not not needed

[github-actions[bot]]

APK file: https://www.kaminsky.me/nc-dev/android-artifacts/12792.apk



To test this change/fix you can simply download above APK file and install and test it in parallel to your existing Nextcloud app.

[github-actions[bot]]

Codacy

Lint

Type	master	PR
Warnings	72	72
Errors	3	3

SpotBugs

Category	Base	New
Bad practice	66	66
Correctness	70	70
Dodgy code	349	349
Experimental	1	1
Internationalization	7	7
Malicious code vulnerability	2	2
Multithreaded correctness	6	6
Performance	57	57
Security	19	19
Total	577	577