pyhttpd: fix built-in module loading, add venv support

pyhttpd: fix built-in module loading, add venv support

* detect statically compiled modules via `httpd -l` and skip
  LoadModule for them, fixing startup failure when log_config_module
  (or others) are built into the httpd binary

* add pyproject.toml with all required Python dependencies
  (cryptography, python-multipart, websockets, pyopenssl, etc.)

* add runtests-pyhttpd.sh that creates/reuses a .venv via uv or
  plain python3+pip, mirroring pytest_suite/runtests.sh

* prepend .venv/bin to PATH when launching httpd so CGI scripts
  forked by httpd also use the venv's Python and find all packages

* update run-all-tests.sh to delegate pyhttpd runs to the new script

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1934947 13f79535-47bb-0310-9956-ffa450edef68