opam env --switch=SWITCHDIR is not quoted in PowerShell

[jonahbeckford]

I'll send PR.

After creating a local Opam switch in a Windows PowerShell 5 directory with a space, like:

mkdir "Person 1"
cd "Person 1"
opam dkml init

the switch suggestion shows:

# Run (& opam env --switch=C:\Person 1) -split '\r?\n' | ForEach-Object { Invoke-Expression $_ } to update the current
shell environment

That needs to be:

(& opam env --switch="C:\Person 1") -split '\r?\n' | ...