Make it possible to build MicroBenchmarks.sln from Visual Studio

[adamsitnik]

Today I have tried to open MicroBenchmarks.sln from a fresh copy of the repo (no previous builds or restores) and I have failed.

I really want to make it easy for devs to work with the existing benchmarks and add new ones so I decided to fix it.

This PR simplifies few things and makes it work again.

Before:

After:

[adamsitnik]

Hmm half of the legs passed, half not. All failed with the following mysterious error:

[2019/06/27 07:20:29][INFO] C:\dotnetbuild\work\13569cd3-3350-425d-bde6-31617d575c36\Payload\artifacts\obj\Reporting\Release\netstandard2.0\Reporting.AssemblyInfo.cs(18,19): error CS0234: The type or namespace name 'Resources' does not exist in the namespace 'System' (are you missing an assembly reference?) [C:\dotnetbuild\work\13569cd3-3350-425d-bde6-31617d575c36\Payload\src\tools\Reporting\Reporting\Reporting.csproj]

[2019/06/27 07:20:29][INFO] Build.cs(8,22): error CS0234: The type or namespace name 'Serialization' does not exist in the namespace 'System.Runtime' (are you missing an assembly reference?) [C:\dotnetbuild\work\13569cd3-3350-425d-bde6-31617d575c36\Payload\src\tools\Reporting\Reporting\Reporting.csproj]

[2019/06/27 07:20:29][INFO] Reporter.cs(10,14): error CS0234: The type or namespace name 'Linq' does not exist in the namespace 'System' (are you missing an assembly reference?) [C:\dotnetbuild\work\13569cd3-3350-425d-bde6-31617d575c36\Payload\src\tools\Reporting\Reporting\Reporting.csproj]

[2019/06/27 07:20:29][INFO] Test.cs(7,14): error CS0234: The type or namespace name 'Linq' does not exist in the namespace 'System' (are you missing an assembly reference?) [C:\dotnetbuild\work\13569cd3-3350-425d-bde6-31617d575c36\Payload\src\tools\Reporting\Reporting\Reporting.csproj]

I can not reproduce it locally... need to wrap my head around it

[ViktorHofer]

Awesome that you switched to Directory.Build.props 👍👍👍

[adamsitnik]

The PR is ready for review, @billwert @jorive PTAL. I added comments and explanations to all the weird things that are not obvious (they were many...).