Set correct storage path for SDK sandbox

For WebView to run in an sdk sandbox process, Context.getDataDir() needs
to return the shared sandbox storage. This CL sets the value in
LoadedApk while binding the application and modifies bindSdkSandbox API
to take in the client app package name to use in the path.

Test: Manual, check that WebView in sandbox tries to access sandbox
shared storage
Bug: 216284889

Change-Id: I1f8bb7e533d155050710866b80047ec849a98f35