Improve notNeededPackages.json testing

[ghost]

Currently we don't do any testing when notNeededPackages.json is changed. When a package is added to it we should ensure:

• The directory it was in no longer exists.
• Nothing depends on it.
• The asOfVersion is higher than the last published version.

[sandersn]

Also check that

1. libraryName matches a real npm name.
2. asOfVersion matches, for major.minor, a real version of the npm package.

When (1) is false, types-publisher crashes currently.