checks: Fix E402 Flake8 in for wxGUI Sphinx doc

[arohanajit]

Fixed E402 error in gui/wxpython/docs/wxgui_sphinx - moved import module to the top

[echoix]

What I see here is that the check for gisbase was made probably to prevent loading grass.script core if not set. However, if it were that important, it would've been a pattern we see everywhere.

Does @wenzeslaus know if we are more robust now and the import can be done and the check after? If so, that PR is fine to merge!

[wenzeslaus]

It seems to be that this code was never doing anything useful. Adding etc/python/grass to sys.path does not make grass.script importable which is clearly the intention here (an import after a sys.path.append call).

You can just remove the whole block with GISBASE. Who wants to compile the documentation, needs to have grass on path - that's not such an unexpected requirement at this point. GISBASE may not even be needed on the other hand.

If I'm not mistaken, we don't compile wxGUI doc anywhere on servers, so this should be very safe to mess with.

[arohanajit]

Got it, I'll remove that code block. I'll also remove sys and os library imports since that was the only place where they are used and will highlight new flake8 errors

[echoix]

I fixed the merge conflict