PDF Gen - Construct an API for generating selected forms and return generated PDFs

Create an endpoint that can be used with a GET method with parameters (can be a single string or a list of strings), and returns selected generated PDF form(s).
(Reference: https://github.com/bcgov/lear/blob/main/legal-api/src/legal_api/services/pdf_service.py#L73C3-L112C22)

**NOTE**
- Look at Legal-Api repo for references, if not familiar with flask and how to create API endpoints.

TODOs
- [ ] Import bp_pdf and related flask functions
- [ ] Import related model(s) and methods
- [ ] Create a function to get a list of generable forms
- [ ] Add an endpoint / route to make the API work
- [ ] Add/Update tests if necessary
- [ ] Make sure to test the endpoint in Postman, consider successful and failed requests