Add sdktool specific tools into QtCreator's PATH environment

In my qtcreator.ini from c:\Qt\Tools\QtCreator\share\qtcreator\QtProject\QtCreator.ini

I have:

[CMakeSpecificSettings]
NinjaPath=C:\\Qt\\Tools\\Ninja\\ninja.exe

[ConanSettings]
ConanFilePath=C:\\Qt\\Tools\\Conan\\conan.exe 

I think it would be better if the new Qt Creator wide environment settings would contain a PATH entry with C:/Qt/Tools/Ninja and C:/Qt/Tools/Conan.

This way it would be transparent for the user which additional paths are added to PATH and we'll remove some custom hacking of the environment for these tools.