Add support for activating Python venv when switching between repositories

Many Python users work with virtual environments (venvs), typically one per project. For pre-commit hooks to run correctly, the appropriate venv must be active; otherwise, issues such as missing modules can occur (e.g., Pylint will report "module missing" errors if the wrong venv is being used).

A workaround that currently can be used is to launch SmartGit via scripts individually crafted per project to activate the respective venv, e.g.:

call C:\Users\username\PycharmProjects\project_name\.venv\Scripts\activate  
C:\Apps\SmartGit\bin\smartgit.exe  

However, this is not a general solution, since SmartGit allows users to switch between projects within the tool, which leads to the wrong venv being used again. It would be great if there was a way to have Smartgit automatically activate the correct venv of the respective project.