Split nuget packages to manage Codeable.Foundation

[watfordsuzy]

This is an alternative to #3.

This PR does three things:

1. Converts the projects to the new SDK style to take advantage of all of the major QOL improvements.
2. Converts the references to PackageReferences and uses transitive references whenever possible.
3. Uses Nugetizer to infer the correct means to build the .nupkg files from the projects.

This would now allow anyone who did not need the Web references to instead simply pull Codeable.Foundation as they did before. Web users would then need to pull Codeable.Foundation.Web (an as yet undistributed package).