Add infrastructure for creating diagnostics for general API usage

[mjrousos]

This adds an analyzer (without code fix provider) for identifying and flagging usage of configured namespaces, types, or members and creating diagnostics with associated messages.

This will allow easily notifying users if they're using namespace, types, or members that are known to require manual changes.

Fixes #621
Fixes #502
Fixes #65
Fixes #69
Fixes #75

[mjrousos]

@twsouthwick, I've updated the PR based on your feedback (thanks!). Can you take another look?

Also, I removed launchSettings.json which it looks like you added last week but I think is unnecessary since I don't want to have a git change (or, worse, conflict) every time I f5 UA against a different project locally. Let me know if there's a reason you prefer committing the file.

[twsouthwick]

The launchsettings.json change was so it would get launched with "development" enviornment so it won't send telemetry on dev work. Happy to explore other options there

[twsouthwick]

A few comments, but otherwise LGTM

As for the localizability, I'm fine punting that, but we should identify any architectural choices to make sure we won't cause breaking changes to introduce it.

[mjrousos]

Yea, I see why you changed launchsettings.json. I'll change it back to how you had it. I don't like having that file be always modified (and never committed) on my dev machine, but I can't think of a better alternative.