BUG-5280: use a lambda for createLocalHistory()/close()

BUG-5280: use a lambda for createLocalHistory()/close()

These are internal commands, which can be efficiently implemented
using a simple delayed execution primitive.

Introduce ClientActorContext#executeInActor(), which will wrap
a specialized subclass of Runnable and send it to the actor.

This can be used to dispatch lambdas to methods, reducing the need
for specialized messages and instanceof checks.

Change-Id: Id5cd388657a274d551892a6c943b062d70c7bea7
Signed-off-by: Robert Varga <rovarga@cisco.com>