Preserve annotations from initial FIRRTL pass

[nhynes]

This PR fixes an issue where new/updated annotations from the initial compiler pass are not passed to the following lowering pass.

Related: chipsalliance/chisel#968

[ducky64]

This looks fine. Though it also seems like a bit of a gotcha (it's not immediately obvious that one needs to modify the options after the FIRRTL run to pass through annotations), but I assume this is something that will be fixed by annotations as options?

[nhynes]

this is something that will be fixed by annotations as options?

Yep, I can successfully load bundle memories from file now. I think that the root issue is that the emitted FIR string doesn't actually contain any of the annotations--they're stored separately in the CircuitState, so unless that is passed into treadle wholesale, they have to be added through options.

[jackkoenig]

I believe that Annotations as options will fix this because it is generalizing everything (including CircuitState) into Annotations which will then be what is passed to everything (including treadle)