feat(wpcarro/emacs): Support terraform-mode

I "think" this belongs in `wpc-language-support.el`, because I need it mostly to
render `*.hcl` files.

Change-Id: I93106c4912699245449328608c12d4f7c74b4fff
Reviewed-on: https://cl.tvl.fyi/c/depot/+/5563
Tested-by: BuildkiteCI
Reviewed-by: wpcarro <wpcarro@gmail.com>
Autosubmit: wpcarro <wpcarro@gmail.com>

users/wpcarro/emacs/.emacs.d/wpc/wpc-language-support.el

@@ -30,6 +30,7 @@
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 
 (use-package csharp-mode)
+(use-package terraform-mode)
 
 (provide 'wpc-language-support)
 ;;; wpc-language-support.el ends here