Create sTestDir before starting MediaProvidrForFuse tests

MediaProviderForFuse tests use Pictures directory to create files.
Pictures is a top-level directory and always exists. However, some tests
delete some of the top-level directories. Hence we will have to create
Pictures directory when directory doesn't exist.

This change tries to create sTestDir. If directory already exists mkdir
will fail, hence we don't assert for directory creation.

Bug: 156436397
Test: atest MediaProviderForFuseTest
Change-Id: I52a47f0f42d256cb7f562c68a6631dda48fa4b1f
1 file changed