Any command using meta.defaultFlagSet *might* occasionally exit before
the flag package's output got written. This caused flag error messages
to get lost. This PR discards the flag package output in favor of
directly returning the error to the end user.
A lot of commands used `c.Meta.flagSet()` to create the initial flagset for the command, while quite a few of them didn’t actually use or support the flags that are then added.
So I updated a few commands to use `flag.NewFlagSet()` instead to only add the flags that are actually needed/supported.
Additionally this prevents a few commands from using locking while they actually don’t need locking (as locking is enabled as a default in `c.Meta.flagSet()`.
Shell tab completion for all of the subcommands under
"terraform workspace", providing the appropriate kind of auto-complete for
each argument, along with completion for for any flags.
This command serves as an alternative to the human-oriented list of workspaces for scripting use-cases where it's useful to know the _current_ workspace name.
Kristin Laemmert