Add `terraform-lsp` and a small example project to `lsp-mode` docker image

[Gastove]

emacs-lsp/lsp-mode#1147 added support for Terraform development using terraform-lsp. The binary needs to be added to the project Docker image, along with a sample project.

[rnikoopour]

I'm still digging into this and figuring out how to properly do this. One of the issues is that the currently supported terraform-lsp in lsp-mode only supports a certain version of Terraform.

I'm digging into how one could provide the terraform version they need to run to be passed into the container start up. This would allow users to install the correct version of TF into the container that's going to process the code.

Part of this requires getting terraform-ls by Hashicorp incorporated into lsp-mode.