Even though there is an abstract class to represent the interface of an IPA,
the threaded and IPC versions are still multiplexed using the same type,
which uses a boolean to actually dispatch to the right function.
Instead of doing that, split the classes into "threaded" and "isolated"
variants, and make `IPAManager` choose accordingly.
Signed-off-by: Barnabás Pőcze <barnabas.pocze@ideasonboard.com>
Reviewed-by: Paul Elder <paul.elder@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
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