Added package repository path lookup order
- Implement package repository lookup logic in kpm and runtime
- Share ResolveRootPath implementation
- Added packages parsing for global.json file
- packages flag overrides all lookup rules
- Always set packages location when doing a kpm pack
- Resolve the full packages path from global.json
Added support for KRE_PACKAGES_CACHE
- Cleaned up PackageRepository and made it lazy
- Remove extra constructor for NuGetDependencyResolver
- Made DefaultPackagePathResolver resolve based on name and version
- Made the rest of kpm pack use the DefaultPackagePathResolver for consistency