Consolidated protobuf construction by the JNI scheduler driver.
Consolidated protobuf construction by the JNI scheduler driver.

This patch converts the copy-pasted internals of numerous
`construct<>()` specializations for protobufs into a single
template.

Review: https://reviews.apache.org/r/72875

abudnik/mesos,reneploetz/mesos,abudnik/mesos,abudnik/mesos,Gilbert88/mesos,abudnik/mesos,Gilbert88/mesos,reneploetz/mesos,dforsyth/mesos,dforsyth/mesos,abudnik/mesos,Gilbert88/mesos,dforsyth/mesos,dforsyth/mesos,Gilbert88/mesos,dforsyth/mesos,abudnik/mesos,dforsyth/mesos,dforsyth/mesos,reneploetz/mesos,Gilbert88/mesos,Gilbert88/mesos,reneploetz/mesos,reneploetz/mesos,abudnik/mesos,reneploetz/mesos,Gilbert88/mesos,reneploetz/mesos