Test opening file handles with different permissions.
Test opening file handles with different permissions.

These were problematic for vfs2 gofers before correctly implementing separate
read/write handles.

PiperOrigin-RevId: 329613261

google/gvisor,google/gvisor,google/gvisor,google/gvisor,google/gvisor,google/gvisor,google/gvisor,google/gvisor