fix(iosAdapter): fixed issue when user has custom scoop path

[wiedikerli]

I installed scoop on a custom path like:

[environment]::setEnvironmentVariable('SCOOP','D:\Resources\Scoop','User')
$env:SCOOP='D:\Resources\Scoop'
iex (new-object net.webclient).downloadstring('https://get.scoop.sh')

When I tried to start, it failed because it could not find ios_webkit_debug_proxy.exe.
Which Is obvious when scoop is not installed in the user folder.
I added a check if there is a environment variable SCOOP and take this path.