Escape characters for workspace selection

[aanogueira]

This PR aims to fix workspace selection for cases where the namespace starts with special characters, such as -.

[hashicorp-cla]

All committers have signed the CLA.

[aanogueira]

Could I please get some review?

[ferrastas]

@radeksimko @kmoe sorry to poke you directly, but I just saw that you have been recently approving and merging other PR.
We now need to use a fork of the library because of this tiny issue. 😓
Thanks!

[ferrastas]

Just a quick example:

 $ terraform workspace list
* -dev
  -org
  -stag

...

$ terraform workspace select -org
Usage: terraform [global options] workspace select NAME

  Select a different Terraform workspace.

Options:

    -or-create=false    Create the Terraform workspace if it doesn't exist.
Error parsing command-line flags: flag provided but not defined: -org

...

$ terraform workspace select -- -org
Switched to workspace "-org".

[bflad]

One of the challenges here is that human-readable outputs in Terraform are not protected by compatibility promises, so relying on the existing output might break in future versions.

There are some recent discussions/issues around this:

• Change workspace list indicator from asterisk to greater-than symbol terraform#34750 (comment)
• Requesting machine-enumaratable workspace listing terraform#34775

I think ideally, Terraform CLI would have an enhancement on the existing command, such as a -json flag, for machine-readable output. That output (and this library) would be protected from potentially unexpected changes.