Most of the state package has been deprecated by the states package.
This PR replaces all the references to the old state package that
can be done simply - the low-hanging fruit.
* states: move state.Locker to statemgr
The state.Locker interface was a wrapper around a statemgr.Full, so
moving this was relatively straightforward.
* command: remove unnecessary use of state package for writing local terraform state files
* move state.LocalState into terraform package
state.LocalState is responsible for managing terraform.States, so it
made sense (to me) to move it into the terraform package.
* slight change of heart: move state.LocalState into clistate instead of
terraform
Fix the now failing state unlock test by reporting the correct ID.
The ID used by GCS is the generation number of the info object, which
isn't known until the info is already written out. While we can't get
the correct ID from the info data for the error rmessage, we can update
it with the generation number after it's read.