Options for time-partitioning in GBQ are included

[dkapitan]

We often want time-partitioning on tables, e.g. to separate CBS data from subsequent years. We need to choose and implement how to best create time partitioning:

• At ingestion time from source files via LoadJob: need to specificy schema beforehand, which may be unnecessary overheid
• During QueryJob when creating datamarts: seems easiest, because it can be included in StandardSQL