refactor(devtools): improve formatting of injector providers token labels

Use `InjectionToken.toString` for the string representation of `InjectionToken`s for better readibility.

(cherry picked from commit 9f4c025531)

devtools/projects/ng-devtools-backend/src/lib/component-tree/component-tree.ts

@@ -407,7 +407,7 @@ const getDependenciesForDirective = (
 
 const valueToLabel = (value: any): string => {
   if (isInjectionToken(value)) {
-    return `InjectionToken(${value['_desc']})`;
+    return value.toString();
   }
 
   if (typeof value === 'object') {