[BACKEND] Add Stripe service route testing

[jeffplays2005]

Use local stripe testing.

Command line commands:

yarn dev-server

^ Starts development test server

stripe listen --forward-to localhost:8000/webhook

^ Copy the webhook signing secret and set the .env, STRIPE_LOCAL= key to the secret key.

stripe trigger checkout.session.completed

^ Trigger a test event

Is your feature request related to a problem? Please describe.
It would be best to add a route testing for Stripe web hooks, would make development process easier for webhook testing.

Describe the solution you'd like
A clear and concise description of what you want to happen.
Create a yarn stripe-test script, similar to yarn firebase-test.

Describe alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered.

Additional context
Add any other context or screenshots about the feature request here.

BEFORE MERGING

• Integration test written for services
• Schemas annotated if adding new models
• Code generation run (hint: yarn workspace server tsoa spec-and-routes)
• Appropriate mocks created where possible
• PR Reviewed (For non-trivial changes)
• Changes tested after rebasing on master or merging in master (hint: git fetch origin master:master, then git rebase master or git merge master)
• All required PR checks passing