Add angular monorepo to renovate config

The default config groups angular, angular-cli and angularmaterial as separate monorepos and thus the peer dependencies fail to update correctly.
Also decreased the update frequency to monthly

Change-Id: I72d113fe1f6cad2c38f7d97c4c6983df4a0ca30d
Test: N/A
Bug: N/A
GitOrigin-RevId: 6a630515f56232b7a1c47c2b2a6c109363b82b54

renovate.json5

@@ -19,6 +19,15 @@
           "golang.org/x/tools"
         ],
         "schedule": ["every month"]
+      },
+      { // Update angular monorepo packages once a month.
+        "matchSourceUrlPrefixes": [
+          "https://github.com/angular/angular",
+          "https://github.com/angular/angular-cli",
+          "https://github.com/angular/components",
+        ],
+        "schedule": ["every month"],
+        "groupName": "angular+cli monorepo"
       }
     ]
 }