Write scripts to generate terraform provider Kconfigs automatically

[chucklever]

Building the Kconfig menus for the various cloud options should be pretty rote -- the provider's options are available via a command line tool (such as "aws" or "az"), the output of which is generally some form of JSON. It should be easy (ie scriptable) to translate that JSON output into Kconfig. Such scripts could be run with regularity to update the Kconfig menu choices with up-to-date resource selections.