Restructure repo

[viceice]

We should restructure repo to a more conventional dotnet project

• add main project to MimeMapping folder refactor: Restructure repo #98
• move projects to src and test folders refactor: Restructure repo #98
• use central versioning
• add global.json

[gintsk]

Yes, to better align with other .NET projects we can split the root into src and test with MimeMapping.sln in the root folder.

Maybe we should also use the new artifacts output and global.json

[viceice]

@gintsk do you like to do this?

[gintsk]

Yes, I would like to.

[gintsk]

Maybe we should rename Test project to MimeMapping.Tests and move it to src\MimeMapping.Tests ?

[viceice]

@gintsk PR merger 🎉 Do you like to continue with next points?