[autotest] Support sharding for getting HQEs and special tasks

Following 2 RPCs that are used by AFE java client are improved
to support sharding.

get_host_queue_entries_and_special_tasks
get_num_host_queue_entries_and_special_tasks

BUG=chromium:462819
DEPLOY=afe,apache
TEST=puppylab. Get HQEs and special tasks for a lumpy host
     which is sharded from the master AFE.

Change-Id: I68c0d1a70fb6b61034c755d3a2b7f26475994bb0
Reviewed-on: https://chromium-review.googlesource.com/268523
Reviewed-by: Mungyung Ryu <mkryu@google.com>
Commit-Queue: Mungyung Ryu <mkryu@google.com>
Tested-by: Mungyung Ryu <mkryu@google.com>
7 files changed