This reverts the changes to Windows where Release() was called every
time, since we need share a single DX context across multiple encoders.
Instead introduce a ReleaseSessionData() function and some platform
specific session data that will be passed to it. We use this to track
the VA-API display and fd to release them at the right time. Leaking
displays will also lead to cache pollution in the intel-media-driver
crashing users so we cannot do that.
fixes#9611
9d4b916248