PDF Gen - Construct an API for getting all generable forms

Create an endpoint that can be used with a GET method with no parameters, it returns a list of all generable forms in a JSON format. The results contain the PDF form names and their parameter for generating that PDF.

**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