Be consistent in blocking provider API function (async param vs `...AndWait` name)

[toddbaert]

We should improve the consistency of the function for setting a provider and blocking. In some cases we have an async param, and in others we use an ...AndWait function name.

Background:

I dislike that we mix ...AndWait and aysnc bool in our public API - it's inconsistent - but this isn't something you introduced, it already existed elsewhere. I think in v2 we should go for one or the other (the spec doesn't dictate function naming so we have flexibility here).

Originally posted by @toddbaert in #442