[BEAM-2431] Add GRPC to Compilation of the Runner API

[tgroh]

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Generates the JobService GRPC classes.

[tgroh]

R: @sb2nov

[sb2nov]

LGTM if tests pass.

[tgroh]

retest this please

[tgroh]

retest this please

[tgroh]

AMQPIOTest seems to be timing out; I don't believe the two are related, but I'm going to give it one more go before investigating further.

[coveralls]

Coverage decreased (-0.2%) to 69.975% when pulling 006db74 on tgroh:job_submission_api_java into f731de0 on apache:master.