fix(@schematics/angular): show routing module suffixes in findModule error

When only routing modules are found, the error message printed the optional
`routingModuleExt` parameter, which no schematic passes, so users saw
"Modules with suffix 'undefined' are strictly reserved for routing.". Since
0b7d48c the lookup checks both `-routing-module.ts` and `-routing.module.ts`,
so list the suffixes that are actually used.

(cherry picked from commit 490a6fe)

Author: MeAkib

packages/schematics/angular/utility/find-module.ts

@@ -117,7 +117,7 @@ export function findModule(
 
   const errorMsg = foundRoutingModule
     ? 'Could not find a non Routing NgModule.' +
-      `\nModules with suffix '${routingModuleExt}' are strictly reserved for routing.` +
+      `\nModules with suffix '${routingModuleExtensions.join("' or '")}' are strictly reserved for routing.` +
       `\nUse the '--skip-import' option to skip importing in NgModule.`
     : `Could not find an NgModule. Use the '--skip-import' option to skip importing in NgModule.`;
 

packages/schematics/angular/utility/find-module_spec.ts

@@ -56,6 +56,9 @@ describe('find-module', () => {
       expect(() => findModule(host, 'foo/src/app/anything-routing')).toThrowError(
         /Could not find a non Routing NgModule/,
       );
+      expect(() => findModule(host, 'foo/src/app/anything-routing')).toThrowError(
+        /Modules with suffix '-routing-module\.ts' or '-routing\.module\.ts' are strictly reserved/,
+      );
     });
 
     it('should throw if two modules found', () => {