Change Roman detector naming from SCAxy to WFIxy

[Skyhawk172]

For consistency with other Roman simulation tools as well as with the Roman pipeline, we would like to specify which detector to use with the WFIxy string instead of SCAxy.

For example, users would use the following going forward:
wfi.detector = "WFI01"

[mperrin]

This can be done in part similarly to how we handle NRCA5 and NRCALONG, with a couple lines of code in the detector setter function to treat both values as synonyms. See https://github.com/spacetelescope/webbpsf/blob/develop/webbpsf/webbpsf_core.py#L2784

That would let existing code using "SCA01" to continue to work, while new code can be written using "WFI01", and both would behind the scenes set the detector to the same value.