Run lint/docs/generate etc. steps along the unit tests

The CI runs several required jobs such as lint/docs/generate/docker-tests etc... other than unit tests. Whenever a check fails on CI, as a contributor I would like to run the same locally and fix it. The current setup is mainly optimized towards the CI where all the packages are installed and linted in one step. It's not friendly to developers, it makes me install all the libraries even though I am not touching them. When this installation step fails, for any reason, from missing libpq headers in psycopg2 to strange errors originating from the C compiler in grpcio, I am blocked and can't make any progress.

I shouldn't need to worry about any other packages when I want to make a bug fix or enhancement to FastAPI instrumentation. This proposal is to update the tooling to make any checks related to a package put together and run as part of a single command tox -e test-instrumentation-fastapi.

Start by inspecting the repository's current CI and tox configuration to see how lint, docs, generate, Docker tests, and unit tests are grouped. Done means a command such as tox -e test-instrumentation-fastapi runs the checks for one package without requiring unrelated package dependencies.