Introduce program UUID for Workbench programs. This program UUID is then used in crop schema (project table) to discriminate Nurseries/Trials/Datasets and Folders that are program specific.

Issue: BMS-149
Reviewer: RebeccaB
Removed Program and link tabled introduced earlier. Reverted this approach in favour of a column in project table that soft references workbench projects via program UUID.

Issue: BMS-149
Reviewer: RebeccaB