feat: Add "coder" CLI (#221)

* feat: Add "coder" CLI

* Add CLI test for login

* Add "bin/coder" target to Makefile

* Update promptui to fix race

* Fix error scope

* Don't run CLI tests on Windows

* Fix requested changes

cmd/coder/main.go

@@ -1,7 +1,14 @@
 package main
 
-import "fmt"
+import (
+	"os"
+
+	"github.com/coder/coder/cli"
+)
 
 func main() {
-	_, _ = fmt.Println("Hello World!")
+	err := cli.Root().Execute()
+	if err != nil {
+		os.Exit(1)
+	}
 }