Add option for `show` output

[vladkasianenko]

There's no way to save the output from the show command.

terraform show -json > $(Build.ArtifactStagingDirectory)/tfstate.json is what I run as a bash command instead. I guess it would be nice to have this command so there's possibility to save output (binary or json).

[charleszipp]

@vladkasianenko would you have any concerns about the file potentially containing sensitve data such as access keys and passwords? What expectations if any would you have of the task to protect the data written to this file?

[Dilergore]

I think it is important to have this option. There are IaaC scanning tools requiring you to be able to run show with -json and output a file so the generated json formatted plan file can be used for scanning.

[yunxi-zhang]

Really want this feature to be added, cos the show results could be used along with shell scripts for further processing.