feat: Replace _customButtons with generatorUrl for S.to-like Generator

- Added generatorUrl property (new schema addition)
- Removed redundant _customButtons
- Will now show green '🚀 Generate' button automatically
- Cleaner implementation using new generatorUrl feature

Author: Bluscream

sources.json

@@ -2722,13 +2722,7 @@
             ]
         },
         "note": "⚠️ This is a generator tool! Visit https://grayjay-sources.github.io/grayjay-source-sto-like/ to create your custom plugin",
-        "_customButtons": [
-            {
-                "text": "Generate",
-                "url": "https://grayjay-sources.github.io/grayjay-source-sto-like/",
-                "classes": "btn-secondary"
-            }
-        ]
+        "generatorUrl": "https://grayjay-sources.github.io/grayjay-source-sto-like/"
     },
     {
         "name": "Sample",