Improve target host configuration

[fusepilot]

This simplifies the host configuration. And in spirit with CRA, targets all known Adobe hosts by default with the version set to [0.0,99.9]. So now, instead of users having to find the right host id and version for whichever app they're targeting, it will just work.

[fusepilot]

This still doesn't allow for configuration of specific host name and host version combos. I'd prefer to not add additional configuration somewhere else, either in package.json or something like a cep.json unless its really necessary since it doesn't really jibe well CRA philosophy.

If it is needed though, we could do something like:

EXTENSION_HOSTS="PHXS@[16.0,16.9], AEFT@[13.5,16.0]"

What do you think @kennethormandy?

[kennethormandy]

Making it support everything by default is a great change, one less decision to make when you’re getting started.

The version number syntax is clear to me, nice that it’s all in one variable again. I agree about avoiding the other config—I didn’t realise that CRA used environment variables, so that all makes more sense to me now.

[fusepilot]

Cool! Thanks for the feedback.