[client] KUDU-3351: Add ResourceMetricsPB into WriteResponsePB

KUDU-1563 adds support for INSERT_IGNORE, UPDATE_IGNORE, and
DELETE_IGNORE. However, it was lacking the per-session metrics about how
many rows get ignored vs modified. This patch implements the per-session
metrics by introducing a new ResourceMetricsPB field into the
WriteResponsePB that's populated in every response sent back to the
client.

Change-Id: I9adefd64b0058c66274a00e1b12334653fcab2b3
Reviewed-on: http://gerrit.cloudera.org:8080/18451
Tested-by: Kudu Jenkins
Reviewed-by: Alexey Serbin <alexey@apache.org>
11 files changed