Add tests to verify "DCIM/Camera" is always visible

Added a test to verify that nomedia presence in DCIM/Camera will not
make the directory hidden, and app can continue to use MediaStore APIs
for files in this directory.

Bug: 168830497
Test: atest ScopedStorageHostTest#testCanWriteToDCIMCameraWithNomedia
Change-Id: I1c68729b40f9615bb2e6021daac100dac710ffe6
2 files changed