Special build for testing main_v4 with additional columns

See test plan in https://bugzilla.mozilla.org/show_bug.cgi?id=1672992

Add X-Source-Tags support to decoded sink

#1329

Support X-Source-Tags header

#1328 Bug 1655477 Support X-Source-Tags header

Rewrite use counter histograms to compact string encoding

#1313 Bug 1646825 Compact encoding for use counter histograms

Add BIG_QUERY_DEFAULT_PROJECT config to sink

#1321 Add BIG_QUERY_DEFAULT_PROJECT config to sink
#1319 Fix missing image builds in edge docker-compose

Fix sink payload format bug

release #1318 to fix #1317

Fix sink payload format bug

release #1297 to fix #1294

ISP metadata

20200521

Add ISP to structured metadata (#1247)

ingestion-sink update

Modify DefaultMaxOutstandingRequestBytes to fix OOM (#1287)

30MB for most jobs, which are allowed up to 1.5G heap.
300MB for BigQuery loads, which are allowed up to 15G heap.

ingestion-sink update

changes since release 20200422 for ingestion-sink/:

• Convert BigQuery.Load integration test to unit test (#1262)
• Skip deleted blobs before BigQuery.Load from PubSub (#1263)