Allow override of the distro to use

[gbraad]

Currently the default distro is assumed. The Process.Start uses wsl without a d option.

For #3 I considered an override for the shell, but thinking of the GetShell function, I think a GetDistro option might also be useful.

eg.

{
  "distro" : "fedora33",
  "shell": "zsh"
}

but also with a possible -d option. I think the configurationbuilder has a CommandLine namespace for this too, though not familiar with this.

PS> $ -d fedora33 ps ax
...
PS> $ -d fedora33
$