#214 create shared auth utility

[tsudhakar87]

ℹ️ Issue

Closes #214

📝 Description

Write a short summary of what you added. Why is it important? Any member of C4C should be able to read this and understand your contribution -- not just your team members.

Briefly list the changes made to the code:

1. Refactored duplicated auth logic into a shared package at shared/lambda-auth/
2. Updated all five lambdas (users, donors, projects, expenditures, reports) to install and use @branch/lambda-auth instead of their own auth implementations
3. Updated each lambda's Dockerfile to build the shared package from source before installing the lambda's dependencies
4. Updated docker-compose.yml to use the monorepo root as the Docker build context (required to include shared/ in the build) and added missing COGNITO_USER_POOL_ID/COGNITO_CLIENT_ID env vars to the users and projects services
5. Added a root .dockerignore
6. Updated the lambda CLI (lambda-cli.js) to auto-generate the auth.ts wrapper on init-handler
7. Moved shared/ into this repo directly instead of pointing it at the C4C shared submodule
8. Updated the github workflows to build the auth package first before installing other deps / running tests

✔️ Verification

1. Run make up
2. Get access token via curl -X POST http://localhost:3006/auth/login -H "Content-Type: application/json" -d '{"email":"<your-email>","password":"<your-password>"}'
3. Hit an authenticated endpoint, I used curl http://localhost:3003/donors -H "Authorization: Bearer <token>" (returns 200 with donor data)
4. Hit the same endpoint without a token, returns 401
5. Hit it with a garbage token (Authorization: Bearer abc), also returns 401

🏕️ (Optional) Future Work / Notes

Did you notice anything ugly during the course of this ticket? Any bugs, design challenges, or unexpected behavior? Write it down so we can clean it up in a future ticket!

Moved the shared directory into this repo, as I don't believe this lambda-auth utility needs to be shared across all of c4c, but let me know if there's another way I should go about this or if the shared submodule is needed