support setting pypiBaseUrl by environment variables and queryParameters; affects [pypi] (#10044)

* support setting pypiBaseUrl by environment variables

* Add support for pypiBaseUrl configuration

* Update Pypi services to include pypiBaseUrl parameter

* change package name example to a more well-known package

* Update custom-environment-variables.yml

* Update Pypi services to include pypiBaseUrl parameter

* fix openapi mismatch

* Update doc/server-secrets.md

---------

Co-authored-by: chris48s <chris48s@users.noreply.github.com>

doc/server-secrets.md

@@ -283,6 +283,13 @@ The Pepy API requires authentication. To obtain a key,
 Create an account, sign in and obtain generate a key on your
 [account page](https://www.pepy.tech/user).
 
+### PyPI
+
+- `PYPI_URL` (yml: `public.pypi.baseUri`)
+
+`PYPI_URL` can be used to optionally send all the PyPI requests to a Self-hosted Pypi registry,
+users can also override this by query parameter `pypiBaseUrl`.
+
 ### SymfonyInsight (formerly Sensiolabs)
 
 - `SL_INSIGHT_USER_UUID` (yml: `private.sl_insight_userUuid`)