This is the first installment to make sure every project is instantiated
with an organization. Here we have introduced a `before_validation`
that sets the project's `organization_id` to the project's root
ancestor's `organization_id`.

The next steps are:

1. Remove default 1 for the `projects.organization_id` column.
2. Check the organization_id column if it's being set to null through
some code path.
3. Fix the above code path and do a backfill.
4. If no nulls are found then add a validation and a null check
   constraint for Project#organization.