Update to Windows data path name, and change to when examples folder is created

[raph-luc]

Resolves issue #1588 for pyfluent

Changes the point of creation of the data and examples paths from when pyfluent is first imported, to when the example files are downloaded.

In addition, before these changes Windows was saving to %LocalAppData%\ansys_fluent_core\ansys_fluent_core\example, after these changes it will save to %LocalAppData%\Ansys\ansys_fluent_core\example. The root directory %LocalAppData%\Ansys is already created when installing Ansys Fluent releases on Windows.

These changes do not influence the default data paths on Linux, only changes them on Windows.

To make things easier for CI/testing or other purposes in the future, we could make __init__.py check for an existing env variable for the data paths, like I noticed ansys/pyprimemesh does. Let me know if anyone thinks this would be useful.

I am going to suggest the same naming change to other pyansys repositories so we all potentially use the same naming scheme and root Ansys folder, and avoid cluttering the user's local app data folder on Windows (and see if they care about folders being created on import regardless of whether they will actually be used or not).

[raph-luc]

start_fluent_container() in fluent_container.py was not checking for existing directories before creating tempfile, and was failing with weird errors due to that when running the tests. Should now be fixed

edit: trying a different fix, now checking the examples_path folder exists for the docker container tests, when fluent is being launched in a docker container