Refactor PowerShell usage to not require local script exec (#97)

Author: arvindsh

Engine/SQLCallStackResolver.Engine.csproj

@@ -123,7 +123,7 @@
   </Target>
   <PropertyGroup>
     <PreBuildEvent>cd $(ProjectDir)
-powershell -File "$(ProjectDir)../utils/getBuildPreReqs.ps1"
+type ..\utils\import-vsenv.ps1 ..\utils\getBuildPreReqs.ps1 2&gt;nul | powershell
 </PreBuildEvent>
   </PropertyGroup>
   <PropertyGroup>

utils/getBuildPreReqs.ps1

@@ -1,8 +1,5 @@
 # Copyright (c) Microsoft Corporation.
 # Licensed under the MIT License - see LICENSE file in this repo.
-
-. "$PSScriptRoot/import-vsenv.ps1"  # import VS environment
-
 if (-not (Test-Path DIA/Dia2Lib.dll)) {
     pushd "$env:TEMP"
     midl.exe /x64 /I "$env:VSINSTALLDIR/DIA SDK/include" "$env:VSINSTALLDIR/DIA SDK/idl/dia2.idl" /tlb dia2.tlb

utils/import-vsenv.ps1

@@ -1,10 +1,8 @@
 # Copyright (c) Microsoft Corporation.
 # Licensed under the MIT License - see LICENSE file in this repo.
-
 $vsMaxVerFound = 0
 $vsPath = (& "${env:ProgramFiles(x86)}/Microsoft Visual Studio/Installer/vswhere.exe" -latest -prerelease -property installationPath)
-if ($vsPath -eq $null) { Write-Error "No Visual Studio installation found. Exiting..." -ErrorAction Stop }
-else { Write-Host "Using Visual Studio from $vsPath" }
+if ($vsPath -eq $null) { Write-Error "No Visual Studio installation found. Exiting..." -ErrorAction Stop } else { Write-Host "Using Visual Studio from $vsPath" }
 
 & "${env:COMSPEC}" /s /c "`"$vsPath\Common7\Tools\vsdevcmd.bat`" -no_logo && set" | foreach-object {
     $name, $value = $_ -split '=', 2