Detect and correctly activate different Python environments

Actually Power BI Desktop will directly invoke python.exe using the path declared in the Options. Sometimes this will lead to a weird error ("ADO.NET: Python script error") when you use conda environments. This is due to the fact that Anaconda requires the environments to be activated.

A workaround is available: just run the Power BI executable from the Anaconda Prompt after activating the environment. This procedure is definitely awkward and makes it useless to have correctly referenced the environment to be used in the Options.