Write compatibility tests for `io` and `io-sim`'s stm APIs

* [ ] `TMVarDefault`
* [ ] `TQueueDefault`
* [ ] `TBQueueDefault`
* [ ] `TArrayDefault`
* [ ] `TSemDefault`
* [ ] `TChanDefault`

A bonus point for designing tests which check that the types have the same laziness semantics (what can be checked with `nothunks`).
