feat: [OSM-347] Return multiple results part 1: Conforming to the CLI plugin interface

We have a big demand for scanning all <TargetFramework>s inside a .csproj file. Currently, we're only scanning the first target we find. This is sub-optimal.

This PR is the first in a series, to keep things tight. The plugin did not adhere to the standards of https://github.com/snyk/snyk-cli-interface which allows for a plugin's inspect() function to return either a single or multiple results.

In order to allow this to happen, a large amount of type guards and other refactoring had to be done. So to not pollute the actual implementation of the solution with too big a PR, this has been split out to a separate PR.

Breaking changes 🙀

~I really don't think this actually is a change that will break anything, but it is nonetheless changing the object that gets returned. Namely, the returned targetRuntime is now runtime.~

~Basically, this is a lie: https://github.com/snyk/snyk-nuget-plugin/blob/cb11cd62dbd2446d441bbc7d0235467ac7eb26e9/lib/nuget-parser/types.ts#L29~

~Since: https://github.com/snyk/snyk-cli-interface/blob/65e87fe5a3bc735f49a6fd5f59ca19e67da090f6/legacy/plugin.ts#L87~

~In any case. I don't see the CLI is really using it, so the blast radius really ought to be nil, for our use cases at least. But this is a public repo, so, who knows.~

Ignore what I said, this will break everything. Keeping .targetRuntime.

snyk / snyk-nuget-plugin

feat: [OSM-347] Return multiple results part 1: Conforming to the CLI plugin interface #172

Breaking changes 🙀