[wpilib] Tunable Values API

[oh-yes-0-fps]

This allows users to more easily fetch values that have been edited from a dashboard. This is important for quickly iterating. If people think a hasChanged method would be a good idea I can add it. If this API is liked I will implement a cpp equivalent.

[github-actions]

This PR modifies commands. Please open a corresponding PR in Python Commands and include a link to this PR.

[oh-yes-0-fps]

I accidentally branched off of my tracer branch, ignore the commit history above

[pjreiniger]

My team has had a similar thing, backed by the persistent Preferences table in wpilib for quite some time.

Our API makes it super easy to "lock" properties so they can no longer be tunable when you are done tuning.

[oh-yes-0-fps]

Persistent values are better left to the Preferences API. Persistent values can cause unintended side effects very easily if you aren't careful and I think it's important to be very explicit with their usage. I want the expectation of this API to be deterministic at bootup unless a dashboard is modifying a tunable topic.

[oh-yes-0-fps]

Another goal is to prevent primitive boxing, that's why the tunable value classes don't share a common parent with a generic for the value type or something.