Issues with detection of Visual Studio installations

[m-kessler]

The function visual_studio_installation_paths does not detect VS 2026 and
has issues when the same major Visual Studio version is installed multiple times (like two installations of VS 2022).

Consider this output of vswhere on an exemplary machine with several Visual Studio installations:

> vswhere -products * -property InstallationPath
C:\Program Files (x86)\Microsoft Visual Studio\2019\BT16.9
C:\Program Files\Microsoft Visual Studio\2026\Professional
C:\Program Files (x86)\Microsoft Visual Studio\2022\BT17.10
c:\Program Files\Microsoft Visual Studio\2022\Professional

visual_studio_installation_paths does not handle this correctly:

from fmpy.util import visual_studio_installation_paths
import pprint

pprint.pp(visual_studio_installation_paths())

Gives:

[(17,
  'C:\\Program Files (x86)\\Microsoft Visual Studio\\2022\\BT17.10\r\n'
  'c:\\Program Files\\Microsoft Visual Studio\\2022\\Professional'),
 (16, 'C:\\Program Files (x86)\\Microsoft Visual Studio\\2019\\BT16.9')]

We see that:

• VS 2026 (18) is not detected
• The paths to both VS 2022 (17) installations are joined into a single string (here printed across two lines, due to pprint)