[ChiselSim] ChiselEnum does not provide peek/poke methods and user-friendly API

[carlosedp]

While rewriting some tests from chiseltest to ChiselSim, I've noticed ChiselEnum is not handled by the Peek/Poke API.

In a test with c.io.inst.peek() should be(inst) where inst is a ChiselEnum.Type, I get: value peek is not a member of chiselv.Instruction.Type.

The closest thing I could get to work is

c.io.inst.peekValue().asBigInt should be(inst.litValue)

Which is very convoluted and not user-friendly.