Update project's external id fields to point to project_url entries

[fyliu]

Overview

We need to update project's external id fields to point to project_url entries, as decided here.

Action Items

• Update github_primary_repo_id, github_org_id, google_drive_id to be FK to project_url rows
  • ERD
  • Spreadsheet
    • add these to new rows in the URLType - Data sheet if they don't exist
  • Code
• check and release ER: docs: project url fields vs project_url #78 from ice box

Resources/Instructions

• update github_primary_repo_id field: no longer the repo id itself, will now be a foreign key to a row in project_url that corresponds to the primary repo
• update github_org_id: no longer the org id itself, will now be a foreign key to a row in project_url that corresponds to the org repo link
• update google_drive_id: no longer the google drive id itself, will now be a foreign key to a row in project_url that corresponds to the google drive