chore(cmd): clean up commands (#9705)

Move infrastructure related commands to under `cmd/infra` and
development stuff to `cmd/dev`. The default build command builds the
regular user facing binaries: syncthing, stdiscosrv, and strelaysrv.

cmd/infra/ursrv/main.go

@@ -0,0 +1,33 @@
+// Copyright (C) 2023 The Syncthing Authors.
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this file,
+// You can obtain one at https://mozilla.org/MPL/2.0/.
+
+package main
+
+import (
+	"log"
+	"os"
+
+	"github.com/alecthomas/kong"
+	"github.com/syncthing/syncthing/cmd/infra/ursrv/aggregate"
+	"github.com/syncthing/syncthing/cmd/infra/ursrv/serve"
+	_ "github.com/syncthing/syncthing/lib/automaxprocs"
+)
+
+type CLI struct {
+	Serve     serve.CLI     `cmd:"" default:""`
+	Aggregate aggregate.CLI `cmd:""`
+}
+
+func main() {
+	log.SetFlags(log.Ltime | log.Ldate | log.Lshortfile)
+	log.SetOutput(os.Stdout)
+
+	var cli CLI
+	ctx := kong.Parse(&cli)
+	if err := ctx.Run(); err != nil {
+		log.Fatalf("%s: %v", ctx.Command(), err)
+	}
+}