Restore the creation of the remote context in sync inflation.

This was mistakenly removed in Android S (in ag/13732454) and could
cause issues if the top-level layout parameters are defined using
resources defined in the AppWidget's package.

Also add some safeguard to avoid crashing if the AppWidgetProviderInfo
doesn't contain a ProviderInfo (which can happen if it's not created by
the system).

Fix: 201744899
Test: Existing CTS tests
Change-Id: Ibb4f2c26a6258ec2c68a7fd1fafe3e5fe3551109