Set permissions for downloaded files

[maazhassan]

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

Related to #35, but that issue is for setting the UID/GID rather than rwx permissions. Current default permissions for downloaded files are 644. This is problematic especially since Kapowarr runs as root, so other services are unable to modify files even if their UID is in the root group. Even when #35 is fixed, I still think there should be an option to explicitly set rwx permissions, especially as other *arr applications have this.

Describe the solution you'd like

Kapowarr should also have a setting in download settings to explicitly set rwx permissions for downloaded files, the same way Radarr/Sonarr do. We should be able to select other permissions like 774, etc.

Additional context

Sonarr permissions section: