Install GitHub.VisualStudio.vsix before testing

VsixTesting will install the .vsix from the same directory as the test
assembly. Copy test assembly to build directory to allow this to happen.

Author: jcansdale

test/IntegrationTests/IntegrationTests.csproj

@@ -18,15 +18,15 @@
     <DebugSymbols>true</DebugSymbols>
     <DebugType>full</DebugType>
     <Optimize>false</Optimize>
-    <OutputPath>bin\Debug\</OutputPath>
+    <OutputPath>..\..\build\Debug\</OutputPath>
     <DefineConstants>DEBUG;TRACE</DefineConstants>
     <ErrorReport>prompt</ErrorReport>
     <WarningLevel>4</WarningLevel>
   </PropertyGroup>
   <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' ">
     <DebugType>pdbonly</DebugType>
     <Optimize>true</Optimize>
-    <OutputPath>bin\Release\</OutputPath>
+    <OutputPath>..\..\build\Release\</OutputPath>
     <DefineConstants>TRACE</DefineConstants>
     <ErrorReport>prompt</ErrorReport>
     <WarningLevel>4</WarningLevel>