Run builds concurrently (#498)

Author: trivikr

smithy-typescript-codegen/src/main/resources/software/amazon/smithy/typescript/codegen/base-package.json

@@ -3,7 +3,7 @@
   "description": "${packageDescription}",
   "version": "${packageVersion}",
   "scripts": {
-    "build": "${packageManager} build:cjs && ${packageManager} build:es && ${packageManager} build:types",
+    "build": "concurrently '${packageManager}:build:cjs' '${packageManager}:build:es' '${packageManager}:build:types'",
     "build:cjs": "tsc -p tsconfig.cjs.json",
     "build:docs": "typedoc",
     "build:es": "tsc -p tsconfig.es.json",
@@ -20,6 +20,7 @@
   },
   "devDependencies": {
     "@tsconfig/recommended": "1.0.1",
+    "concurrently": "7.0.0",
     "downlevel-dts": "0.7.0",
     "rimraf": "^3.0.0",
     "typedoc": "^0.19.2",