There are actually a few different ways to get to this message.
1. Blank state — no previous terraform applied. Start with a cloud block.
1. Implicit local — start with no backend specified. This actually goes
through the same code execution path as the first scenario.
1. Explicit local — start with a backend local block that has been
applied, then change from the local backend to a cloud block. This
will recognize the state, and is a different path through the code in
the meta backend.
This commit handles the last case. The messaging has also been tweaked.
End to end test included as well.
* determining source or destination to cloud
* handling single to single state migrations to cloud,
using a name strategy or a tags strategy
* Add end-to-end tests for state migration.
