[TASK] Move solution config file to root of repository

[MrBisquit]

Description

The solution file (OpenPuppet.sln) file in the OpenPuppet directory needs to be moved up one directory for tests to work correctly.

[MrBisquit]

• OpenPuppet --> src/OpenPuppet
• OpenPuppet.Tests --> src/OpenPuppet.Tests
• OpenPuppet/OpenPuppet.sln --> OpenPuppet.sln

@Samma2009