Call reset() (if it exists) on forward_fn in IMPALAActor.
Call reset() (if it exists) on forward_fn in IMPALAActor.

This avoids inference functions from needing to identify if state needs to be reset on forward call and eliminates costly comparison operations.

PiperOrigin-RevId: 356751631
Change-Id: I3387856b29d38a5f74bd8029e2f032fd270e5ce7

deepmind/acme,deepmind/acme