YSP-683: ONHA program and news migration

[nJim]

YSP-683: ONHA program and news migration

Description of work

• Includes verbose comments and readme to document this migration and to serve as a reference for future migrations.
• Defines migrations for news and program related content for the Office of New Haven Affairs. All migrations are prefixed with onha as they include opinionated decisions that may not apply to future migrations.

Functional testing steps:

• This work is already complete. This PR simply adds the documentation and reference files to the upstream repo.
• These migrations were executed on the ONHA Development multisite.

[dblanken-yale]

@nJim Would it mess up Drupal at all to compartmentalize these into a subfolder? Was thinking a folder for ONHA, a folder for the next one, so it'll be easier to see what was done without seeing a ton of folders. But is that as easy as just creating the folder and Drupal will still pick them all up or will it cause any issues?

[dblanken-yale]

@nJim Any more work to be done in here or is it ready for a merge? I thought there was a bug fix but didn't see it in the commits, so wanted to make sure.