Remove `deque` from files it isn't actually used in. Add it and `stack`
to files that it is - presumably they were previously transitively found
through other includes.
Although I don't plan to bring over new assertions wholesale
into the current qualification branch, it's entirely possible
that various minor changes in main will use the new assertions;
having this basic support in the release branch will simplify that.
(This is why I'm adding the includes as a separate pass from
rewriting the individual assertions)
Calling getImportedModules requires to list the desired kind of imports.
With the new kind of imports this has become cumbersome. Let's simplify
it by offering common sets of imports. Advanced call sites can still
list the desired imports explicitly.
