Add generic read/update/delete commands (#3992)

* Add generic read/update/delete commands

This adds three generic commands that use the resource prefix to
determine the subcommand to run and pass through args over to that
subcommand. Since this occurs very early on and to avoid loading
essentially every internal resource package, I moved subtype definitions
to globals.

This replaces #3967

Co-authored-by: Johan Brandhorst-Satzkorn <johan.brandhorst@gmail.com>

* De-duplicate Subtype code (#4031)

Co-authored-by: Timothy Messier <tim.messier@gmail.com>

---------

Co-authored-by: Johan Brandhorst-Satzkorn <johan.brandhorst@gmail.com>
Co-authored-by: Timothy Messier <tim.messier@gmail.com>

cmd/boundary/main.go

@@ -4,14 +4,11 @@
 package main
 
 import (
-	"math/rand"
 	"os"
-	"time"
 
 	"github.com/hashicorp/boundary/internal/cmd"
 )
 
 func main() {
-	rand.Seed(time.Now().UnixNano())
 	os.Exit(cmd.Run(os.Args[1:]))
 }