chore: Add golangci-lint and codecov (#3)

* chore: Add golangci-lint and codecov

* Use consistent file names

* Format settings.json

* Add golangci-lint and codecov GitHub Actions

* Add base Go file for linting

* Add test coverage

cmd/coder/main.go

@@ -0,0 +1,7 @@
+package main
+
+import "fmt"
+
+func main() {
+	fmt.Println("Hello World!")
+}