feat: Create provisioner abstraction (#12)

* feat: Create provisioner abstraction

Creates a provisioner abstraction that takes prior art from the Terraform plugin system. It's safe to assume this code will change a lot when it becomes integrated with provisionerd.

Closes #10.

* Ignore generated files in diff view

* Check for unstaged file changes

* Install protoc-gen-go

* Use proper drpc plugin version

* Fix serve closed pipe

* Install sqlc with curl for speed

* Fix install command

* Format CI action

* Add linguist-generated and closed pipe test

* Cleanup code from comments

* Add dRPC comment

* Add Terraform installer for cross-platform

* Build provisioner tests on Linux only

.vscode/settings.json

@@ -1,4 +1,7 @@
 {
+  "files.exclude": {
+    "**/node_modules": true
+  },
   "go.lintTool": "golangci-lint",
   "go.lintFlags": ["--fast"],
   "go.lintOnSave": "package",