Fixes related with paths

[jneira]

• a424a6b aims to fix executableExists assumes the existance of "which" #327 using a pure js lib as fallback (as the js lib, used in npmx has some bugs not fixed since long time ago)
• 32375ca tries to fix Haskell extension reports an Uncaught Error, log file is empty #517 expanding the home dir for paths starting with ~

[jneira]

i've tested manually the use of js which, renaming any which command in wsl debian and checking it still resolves the path to the server.