Importing the nslsii package seems to spawn caproto broadcast threads

[jwlodek]

If you import nslsii, and turn on debug logging, you'll see caproto broadcast messages. This is probably undesirable behavior, and should be modified to only occur if the caproto iocs are imported by nslsii. Probably should go along with a re-org of the project around pyproject.toml w/ an optional [caproto] install candidate.