[BEAM-1928] Move WindowingStrategies to runners-core-construction

[tgroh]

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[tgroh]

R: @dhalperi

[tgroh]

Run Dataflow ValidatesRunner

[dhalperi]

LGTM

[coveralls]

Coverage decreased (-0.1%) to 70.037% when pulling 7935452 on tgroh:windowing_strategies_core_construction into fc10065 on apache:master.

[asfbot]

Refer to this link for build results (access rights to CI server needed):
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[tgroh]

Will merge if https://builds.apache.org/job/beam_PostCommit_Java_ValidatesRunner_Dataflow/2798/ is green

[asfbot]

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[coveralls]

Coverage decreased (-0.1%) to 70.037% when pulling 40b3668 on tgroh:windowing_strategies_core_construction into 7fd9c65 on apache:master.

[asfbot]

Refer to this link for build results (access rights to CI server needed):
https://builds.apache.org/job/beam_PreCommit_Java_MavenInstall/9384/
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