cmd/connector-gen: add helper tool for wide app connector configurations

connector-gen can initially generate connector ACL snippets and
advertise-routes flags for Github and AWS based on their public IP /
domain data.

Updates ENG-2425
Signed-off-by: James Tucker <james@tailscale.com>

cmd/connector-gen/connector-gen.go

@@ -0,0 +1,34 @@
+// Copyright (c) Tailscale Inc & AUTHORS
+// SPDX-License-Identifier: BSD-3-Clause
+
+// connector-gen is a tool to generate app connector configuration and flags from service provider address data.
+package main
+
+import (
+	"fmt"
+	"os"
+)
+
+func help() {
+	fmt.Fprintf(os.Stderr, "Usage: %s [help|github|aws] [subcommand-arguments]\n", os.Args[0])
+}
+
+func main() {
+	if len(os.Args) < 2 {
+		help()
+		os.Exit(128)
+	}
+
+	switch os.Args[1] {
+	case "help", "-h", "--help":
+		help()
+		os.Exit(0)
+	case "github":
+		github()
+	case "aws":
+		aws()
+	default:
+		help()
+		os.Exit(128)
+	}
+}