Use folder name instead of solution as project

[alanhamlett]

To match wakatime-cli, which uses the git folder's name, let's do the same when detecting project:

visualstudio-wakatime/Dev17/WakaTimePackage.cs

Line 165 in a3ac3f7

private string GetProjectName()

We should look at the location of the Solution file, or Solution root folder, then use that folder name as project.