venv: make binary or library from C/C++ installable to `./venv/bin/` or `./venv/lib/`

Feature or enhancement

Make C/C++ library or executable which the python library relied on be able to be installed into ./.venv/lib or ./.venv/bin where ./.venv is the path to virtual env root.

Also ./.venv/include/.

As a result, it can be more flexible to add additional C/C++ dependency without system supervisor permission.

Pitch

Sometimes, python libraries depend C/C++ libraries. Currently, the C/C++ library need to installed system wide. It is a great inconvenience.

If a required C/C++ library is not provided by Linux distro. Just install it into virtual env directory without polluting system-wide environment.

For executable, nothing is needed for functionality. For library, it would be solvable by properly setting LIBRARY_PATH and LD_LIBRARY_PATH.

首先追蹤虛擬環境目前如何處理原生函式庫、可執行檔和標頭檔，並注意 .venv/bin、.venv/lib 和 .venv/include。定義 C/C++ 相依項目所需的安裝行為和環境變數行為，然後在實作前找出相關的測試和文件；當 Python 套件無需全系統安裝即可使用此類相依項目時，即視為完成。