WIP: Tagging for code level of user exposure

[rileyjmurray]

This work-in-progress PR means to address #354.

The plan is to keep this PR open and for each of us to periodically update this branch. @enielse has gotten us started with tagging a few modules. Although the process has just begun, we've already found a module that has minimal user exposure and that's "forsaken"! (Ripe for the removing!)

Tips for working on this:

• Pull from GitHub before making changes. There's a chance someone else might have already pushed some work you don't see on your local repo.
• If you're about to spend a while on this (say, more than 15 minutes) then it would probably be a good idea to post here and explain what (sub) folders you're looking at. That way we don't duplicate effort.

CC: @sserita and @coreyostrove.

[sserita]

This is obsolete in favor of #385, from the ionq fork.