Refactored native dependency resolution
- Added a separate (internal) method for accessing the binaries for a dependency, and removed LibraryNativeDependencySet
  - This is used in building model for Visual Studio
- Introduced a NativeBinaryResolveResult that is built up by a series of resolve steps.
- Removed DeferredNativeDependencySet; instead do lazy evaluation in plugins where required.
Disable test on unknown OS (as well as temporarily on windows)
Mentioned breaking change to C++ model in release notes
Don't create separate NativeBinary instances for 'api' requirements
- 'api' linkage requirement is handled by dependency resolver, by adapting 
  the default linkage for a library