feat(@schematics/angular): update tsconfig.json libs to include es2018

Update the lib property in tsconfig.json files for Angular libraries and workspaces to include es2018.

Author: christianliebel

packages/schematics/angular/library/files/__projectRoot__/tsconfig.lib.json

@@ -14,7 +14,7 @@
     "types": [],
     "lib": [
       "dom",
-      "es2015"
+      "es2018"
     ]
   },
   "angularCompilerOptions": {

packages/schematics/angular/workspace/files/tsconfig.json

@@ -14,7 +14,7 @@
       "node_modules/@types"
     ],
     "lib": [
-      "es2017",
+      "es2018",
       "dom"
     ]
   }