* fix(litellm_proxy/chat/transformation.py): support 'user' and all other openai chat completion params
Fixes issue where 'user' was not being sent in request to litellm proxy via sdk
* fix(prisma_migration.py): remove 'use_prisma_migrate' flag, is now default
* docs: cleanup docs
* fix(proxy_cli.py): remove --use_prisma_migrate flag
* refactor: remove references to use_prisma_migrate env var
This is now the default flow for db migrations
* test(tests): add unit testing for litellm_proxy integration
* fix(cost_calculator.py): fix tracking cost in sdk when calling proxy
* fix(main.py): respect litellm.api_base on `vertex_ai/` and `gemini/` routes
* fix(main.py): consistently support custom api base across gemini + vertexai on embedding + completion
* feat(vertex_ai/): test
* fix: fix linting error
* test: set api base as None before starting loadtest
