Set projects organization_id column not null

The projects.organization_id needs to be set as not null. The column has a foreign key constraint already. There is also a Project model validation to ensure presence of organization_id but it's behind a require_organization feature flag which is currently disabled.

This means there's no guarantee that the projects.organization_id column does not contain NULL values.

We need to build a migration that:

• Set any projects.organization_id IS NULL to projects.organization_id = 1 (the default organization ID)
• Set a NOT NULL constraint on the projects.organization_id column.

Implementation Note

Use the following as starting point / reference:

• Batched Background Migration Backfill
• NOT NULL Constraint