feat(@schematics/angular): deprecate legacyBrowsers application and ng-new option

Internet Explorer 11 support is deprecated and will be removed in future versions of the Angular CLI.

Author: alan-agius4

packages/schematics/angular/application/schema.json

@@ -114,7 +114,8 @@
     "legacyBrowsers": {
       "type": "boolean",
       "description": "Add support for legacy browsers like Internet Explorer using differential loading.",
-      "default": false
+      "default": false,
+      "x-deprecated": "Legacy browsers support is deprecated since version 12. For more information, see https://angular.io/guide/browser-support"
     }
   },
   "required": [

packages/schematics/angular/ng-new/schema.json

@@ -136,7 +136,8 @@
     "legacyBrowsers": {
       "type": "boolean",
       "description": "Add support for legacy browsers like Internet Explorer using differential loading.",
-      "default": false
+      "default": false,
+      "x-deprecated": "Legacy browsers support is deprecated since version 12. For more information, see https://angular.io/guide/browser-support"
     },
     "packageManager": {
       "description": "The package manager used to install dependencies.",