Forward port Dataflow PR-431, PR-454, PR-453 to Beam

[peihe]

Forward port:
GoogleCloudPlatform/DataflowJavaSDK#431
GoogleCloudPlatform/DataflowJavaSDK#454
GoogleCloudPlatform/DataflowJavaSDK#453

[peihe]

Diff for BigQueryTableRowIterator (the deprecated fromQuery is not needed in Beam)

< public class BigQueryTableRowIterator implements AutoCloseable {
---
> class BigQueryTableRowIterator implements AutoCloseable {
124,126c123
<    * specified query in the specified project with useLegacySql set to True.
<    *
<    * @deprecated use {@link #fromQuery(String, String, Bigquery, Boolean, Boolean)}.
---
>    * specified query in the specified project.
128,137d124
<   @Deprecated
<   public static BigQueryTableRowIterator fromQuery(
<       String query, String projectId, Bigquery client, @Nullable Boolean flattenResults) {
<     return fromQuery(query, projectId, client, flattenResults, null /* useLegacySql */);
<   }
< 
<   /**
<      * Constructs a {@code BigQueryTableRowIterator} that reads from the results of executing the
<      * specified query in the specified project.
<      */
166c153
<         // DataflowPipelineRunner.
---
>         // DataflowRunner.
261c248
<       return AvroUtils.formatTimestamp((String) v);
---
>       return BigQueryAvroUtils.formatTimestamp((String) v);
333c320
<         // To match that behavior, BigQueryTableRowiterator, and the DirectPipelineRunner,
---
>         // To match that behavior, BigQueryTableRowiterator, and the DirectRunner,

[peihe]

R: @lukecwik
CC: @dhalperi

[lukecwik]

LGTM, merging

[lukecwik]

On line 298, we don't use INITIAL_JOB_STATUS_POLL_BACKOFF, seems like a backport bug at some point in time. Should be addressed in another PR