API - enable 'native' provision of SPMeta2/PnP models

[SubPointSupport]

Metapack API should be able to provision both SPMeta2/PnP models without NuGet packages. SolutionPackageDeploymentService should be able to provide such option.

That need is driven by 3rd party tooling that would be using only model deployment options without NuGet packaging.

That said, API should still run provision in isolation not interfering with the current application domain. That ensures API's ability to run provision under particular tool version, API and runtime.