`ScalarParam`, `ScalarOption` undesirably coercing to `int` about hdl21 HOT 1 CLOSED

We can definitely prevent the confusion by making these all Prefixed or Optional[Prefixed].
Required user-level changes would, for now, be to creating a Prefixed one way or another, e.g.:

import hdl21 as h 
from hdl21.prefix import m 
from hdl21.primitives import Vdc

Vdc.Params(dc=1000*m) # A long-ish way to write "one"
Vdc.Params(dc=h.Prefixed(1, h.Prefix.UNIT)) # A longer one 
Vdc.Params(dc=h.Prefixed(1)) # UNIT becomes the default prefix

Ideally we could make conversions into these inline, e.g. with:

Vdc.Params(dc=1) 

Where this gets converted to Prefixed(Decimal(1)) along the way.
Opened an issue with Pydantic to see whether they can support such a thing.

from hdl21.