Create table project program area xref 45

[del9ra]

Fixes #45

What changes did you make?

• Created project to program area many-to-many relationship by updating project model and creating xref model
• Tested models relationship and API endpoints
• Updated serializers in project and program area serializers

Why did you make the changes (we will use this info to test)?

• To update a shared data store across hackforla.org, vrms, civictechjobs, and tables (onboarding) project

[fyliu]

Combined the commits and rebased to hackforla/main because I rewrote some of the latest history that didn't pass lint (they didn't go through the PR process where the lint checks happen).

[dmartin4820]

Looks good to me and cannot think of further comments. Good work.