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.
We missed this on the initial update pass because this was calling
directly into the module package API rather than going through the Meta
methods that we updated for the new config loader.
m.installModules here is the same method that "terraform init" is using
for this purpose, ensuring the two will behave the same way. This changes
the output a little compared to the old installer, but it still includes
the important information about where each module is coming from.
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()`.
Update the command package to use the new module storage. Move the old
command output strings into the module storage itself. This could be
moved back later either by using ui callbacks, or designing a module
storage interface once we know what the final requirements will look
like.
Alisdair McDiarmid