(GH-667) PowerShell Custom Host - Set $Profile

When running a custom host, it appears all automatic variables are set
but `$profile`. It is empty for all the different profiles.  When the
profile value is empty and the documents folder exists for the
user, set `$profile` to a string value that represents what it would
have been set to in a normal PowerShell scenario. We can get away with
a single value for `$profile` as most scripts do not look at each of the
profiles, only what is returned by the `$profile` string, which is
`CurrentUserCurrentHost`.

We check for the existence of the documents folder because it tells us
that this is not the LocalSystem user, and we don't want to set
`$profile` when the SYSTEM user is running choco.

src/chocolatey/infrastructure.app/services/PowershellService.cs

@@ -465,6 +465,17 @@ private PowerShellExecutionResults run_host(ChocolateyConfiguration config, stri
                         }
                     };
 
+
+                    var documentsFolder = Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments, Environment.SpecialFolderOption.DoNotVerify);
+                    var currentUserCurrentHostProfile = _fileSystem.combine_paths(documentsFolder, "WindowsPowerShell\\Microsoft.PowerShell_profile.ps1");
+
+                    var profileFix = @"
+if ((Test-Path(""{0}"")) -and ($profile -eq $null -or $profile -eq '')) {{
+  $global:profile = ""{1}""
+}}
+".format_with(documentsFolder, currentUserCurrentHostProfile);
+
+                    pipeline.Commands.Add(new Command(profileFix, isScript: true, useLocalScope: false));
                     pipeline.Commands.Add(new Command(commandToRun, isScript: true, useLocalScope: false));
 
                     try