Using a remote backend should be a user decision, not a bundle author decision

[carolynvs]

When the author writes the bundle, they don't know if the end user will have existing terraform accounts/infra. Instead of having the bundle decide if it uses a remote backend or not, it should be optional configuration that the end user may supply when running the bundle. If it's not specified, then bundle state is used instead.

I'm not sure yet what this should look like, more design work is needed, but I wanted to get this out there that we are putting this configuration in the wrong spot.