Update Table: ProjectProgramAreaXref

### Overview

We need to update the ProjectProgramAreaXref table model to have the correct names for fields.

#### Details
- The initial model issue: #45

### Action Items
Update existing Django model
- [ ] In the files indicated by Resource 1.01, Change the following items in the code

| Current Name in code | Updated Name | Updated Type (may already be this type) | FK Table | FK Table Issue(s) |
| -------------------- | ------------ | --------------------------------------- | -------- | ----------------- |
| project_id | project | int | project | #16 & #197 & #227 & #290 & #607 |
| program_area_id | program_area | int | programarea | #43 |

- [ ] Write a test for the new relationships this model will have with other models (e.g., creating a user and assigning them a set of permissions on a project) if any.
- [ ] Update API end point
- [ ] Update API unit tests
- [ ] generate a schema table description (see resources 1.04), post it in a comment below, and add a link to it in the Update Schema dependency issue
- [ ] Document the endpoint in ReDocs (see resources 1.05)

### FK status
- #16
- #197
- #227
- #290
- #43
- #607

### After PR has been approved
- [ ] Release the dependency and move the issue out of the icebox for [Replace with ISSUE NUMBER OF UPDATE ERD]

### Resources
- 1.01 Code locations
- 1.01.01 [/app/core/models.py](https://github.com/hackforla/peopledepot/blob/main/app/core/models.py)
- 1.01.02 [/app/core/admin.py](https://github.com/hackforla/peopledepot/blob/main/app/core/admin.py)
- 1.01.03 [/app/core/api/serializers.py](https://github.com/hackforla/peopledepot/blob/main/app/core/api/serializers.py)
- 1.01.04 [/app/core/api/views.py](https://github.com/hackforla/peopledepot/blob/main/app/core/api/views.py)
- 1.02 [People Depot Resources wiki page](https://github.com/hackforla/peopledepot/wiki/Resources-and-Links) for links
- ERD
- Table and Field Definitions
- API Endpoint
- 1.03 Spreadsheet: [PD: Table and field explanations, Current Field Permission tab](https://docs.google.com/spreadsheets/d/1x_zZ8JLS2hO-zG0jUocOJmX16jh-DF5dccrd_OEGNZ0/edit?gid=749942651)
-1.03.01 [ProjectProgramAreaXref filter](https://docs.google.com/spreadsheets/d/1x_zZ8JLS2hO-zG0jUocOJmX16jh-DF5dccrd_OEGNZ0/edit?gid=749942651#gid=749942651&fvid=2014728616)
- 1.04 [Instructions for how to generate a schema table description](https://hackforla.github.io/peopledepot/contributing/howto/generate-db-table-description/)
- 1.05 [Instructions for how to Document End point](https://hackforla.github.io/peopledepot/contributing/howto/add-model-and-api-endpoints/#add-viewset) step 3