[Bootstrapper] Make Installing Code for Local Install

[nagilson]

📓 Summary

Write something, which, given a directory to install to, installs an sdk, runtime, aspnetcore runtime, or winforms runtime there. The SDK and Runtime can be part of the PR and just a hard-coded file, or a hard-coded link to a singular download. The releases.json logic will later be hooked up to this to enable installing any version.

Additional Context

You may need to consider how to 'track' these installations. As well, you may want to consider that some sdk installs have a runtime within them and we likely don't want to duplicate that. Or, how the aspnetcore runtime zip has a regular runtime zip inside of it.

Again, the DNVM repo has code which already does that which may help serve as inspiration.

Blocked Until These Issues Are Done:

https://github.com/dotnet/cli-lab/issues/347