Warehouse selective sync support

[alex-haproff]

Is your feature request related to a problem? Please describe.

segment_warehouse resource is limited in terms of options that can be supplied upon warehouse creation. One of the much needed options is to be able to specify sources to sync to the warehouse selectively, as per UI and the public API. Without selective sync option the warehouse gets created and an ingestion of all known sources is started.

Describe the solution you'd like When a warehouse is created it would be good to have an option to not sync any sources by default, exclude all from the sync. I would then prefer to explicitly specify source to sync using segment_source_warehouse_connection for each source.