feat: allow `EStateM` to be used polymorphically

[eric-wieser]

This doesn't change IO or ST, but does enable downstream projects like Mathlib to use EStateM for their own purposes with full universe polymorphism.

The alternative is defining an entire copy of EStateM, which is a lot of boilerplate.

Notably, the generalized EStateM.map can be invoked (in the non-monadic spelling) with ULift.up to move between universes.

Summary

Link to RFC or bug issue: this is a prerequisite for #3011, but may be justified in its own right.