feat(@angular/cli): support pnpm as a package manager option

Author: clydin

packages/angular/cli/lib/config/schema.json

@@ -49,7 +49,7 @@
         "packageManager": {
           "description": "Specify which package manager tool to use.",
           "type": "string",
-          "enum": [ "npm", "cnpm", "yarn" ]
+          "enum": [ "npm", "cnpm", "yarn", "pnpm" ]
         },
         "warnings": {
           "description": "Control CLI specific console warnings",

packages/angular/cli/tasks/npm-install.ts

@@ -24,8 +24,9 @@ export default async function (packageName: string,
   const installArgs: string[] = [];
   switch (packageManager) {
     case 'cnpm':
+    case 'pnpm':
     case 'npm':
-      installArgs.push('install', '--quiet');
+      installArgs.push('install', '--silent');
       break;
 
     case 'yarn':