Move SQL engine and PostgreSQL server to their own binaries (#8417)

* Drop SQL engine and PostgreSQL server

* Split SQL tooling into weed-db and weed-sql

* move

* fix building

cmd/weed-sql/main.go

@@ -0,0 +1,7 @@
+package main
+
+import "os"
+
+func main() {
+	os.Exit(Run(os.Args[1:]))
+}