Test palm models by restricting access with project_id

This MR limits access to the PALM models using project_id.
Use cases - https://gitlab.com/gitlab-org/modelops/applied-ml/code-suggestions/ai-assist/-/blob/e66bf103c21d88561fb3208aef18a0f79391c272/tests/codesuggestions/test_api_suggestions.py

How to run locally:

1. Run poetry install in the project root directory

2. Generate a JSON key file for the vertex service account used in the staging cluster. Please, delete it after

3. Update the .env file with the following content:

   GOOGLE_VERTEX_AI_CREDENTIALS="<path to the JSON key>"
   
   AUTH_BYPASS_EXTERNAL=false # required false to test this MR
   TRITON_HOST=host.docker.internal
   TRITON_PORT=8080
   F_IS_THIRD_PARTY_AI_DEFAULT=true # or false 
   
   FASTAPI_DOCS_URL=/docs
   FASTAPI_OPENAPI_URL=/openapi.json
   FASTAPI_API_PORT=5052

4. Run poetry run codesuggestions in the project root directory

5. Send a request using curl to the /v2/completions endpoint with your PAT.

Closes: #146 (closed)