add PubSubToBigQuery dynamic destinations tables

[case-k-git]

add DynamicDestinations options to determine table based on pub/sub message value . using this option reduce dataflow instance cost .

[stale[bot]]

This pull request has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[bvolpato]

Hi @case-k-git -- thanks for your contribution here. Unfortunately we ran behind on reviews, and the structure of the project changed a bit. Is there still interest in pursuing this template? We can work together on a plan to resolve conflicts + review the code.