Fix NuGet packages.lock.json parsing for Project and CentralTransitive types

[marcoberger]

Summary

This fixes parsing of NuGet packages.lock.json files that contain dependency
entries with the Project or CentralTransitive type.

NuGet lockfiles can contain these dependency types in addition to Direct and
Transitive. Before this change, the parser raised an exception for any type
other than Direct or Transitive, which caused parsing to abort and prevented
packages from being reported.

The updated behavior is:

• Direct entries are reported as direct dependencies.
• Transitive entries are reported as transitive dependencies.
• CentralTransitive entries are reported as transitive dependencies.
• Project entries are skipped because they are project references, not NuGet
  package dependencies.

Tests

Added a unit test covering a NuGet packages.lock.json file with Direct,
Transitive, CentralTransitive, and Project entries.

Fixes #5106

Tasks

• Reviewed contribution guidelines
• PR is descriptively titled 📑 and links the original issue above 🔗
• Tests pass -- look for a green checkbox ✔️ a few minutes after opening your PR
  Run tests locally to check for errors.
• Commits are in uniquely-named feature branch and has no merge conflicts 📁
• Updated documentation pages (if applicable)
• Updated CHANGELOG.rst (if applicable)