Rename project to `musicbrainzngs2`

[C0rn3j]

Let's differentiate from the original by adding a 2 to the project name, this should be reflected in the code, in all tests, etc.

Current codebases can always import musicbrainzngs2 as musicbrainzngs.

Not 100% certain the name change is the correct way to go there, since the upstream has been dead for 5+ years maybe we could yoink the current naming from under then, and distributions packaging this would have to conflict?

[jfindlay]

Are you planning to publish to PyPI?

[C0rn3j]

I definitely could provided this PR is sorted

[jfindlay]

how about mbngs2 or just mbngs? musicbrainzngs is already a mouthful to type out and adding a 2 is another straw. At the point of forking is an opportunity of a project rename. Just appending a 2 is a little bit of a confusing borrow from versioning to imply forking. It's true musicbrainzngs2 will be an improvement, and thus warrant a version increase, but it's also a fork and github already shows where it's forked from. Both github and PyPI will surface the project in user searches with the appropriate keyword annotations.