chore: rename keystone to draft

Rename the module, CLI command name, and all references from
keystone/basalt to draft, and fix the stale build/README content
found along the way.

tools/sync_templates.go

@@ -13,7 +13,7 @@ import (
 const (
 	sourceDir      = "assets/testdata/api_tmpl"
 	targetDir      = "assets/embedded"
-	oldModuleName  = "github.com/FernandoJVideira/simple_bank"
+	oldModuleName  = "github.com/FernandoJVideira/api_tmpl"
 	moduleTemplate = "{{ .ModuleName }}"
 )