Revert removal of JSON validator in hassfest (#34504)

Co-Authored-By: Paulus Schoutsen <balloob@gmail.com>

script/hassfest/__main__.py

@@ -9,6 +9,7 @@ from . import (
     config_flow,
     coverage,
     dependencies,
+    json,
     manifest,
     services,
     ssdp,
@@ -18,6 +19,7 @@ from . import (
 from .model import Config, Integration
 
 INTEGRATION_PLUGINS = [
+    json,
     codeowners,
     config_flow,
     dependencies,

script/hassfest/json.py

+"""Validate integration JSON files."""
+import json
+from typing import Dict
+
+from .model import Integration
+
+
+def validate_json_files(integration: Integration):
+    """Validate JSON files for integration."""
+    for json_file in integration.path.glob("**/*.json"):
+        if not json_file.is_file():
+            continue
+
+        try:
+            json.loads(json_file.read_text())
+        except json.JSONDecodeError:
+            relative_path = json_file.relative_to(integration.path)
+            integration.add_error("json", f"Invalid JSON file {relative_path}")
+
+    return
+
+
+def validate(integrations: Dict[str, Integration], config):
+    """Handle JSON files inside integrations."""
+    if not config.specific_integrations:
+        return
+
+    for integration in integrations.values():
+        if not integration.manifest:
+            continue
+
+        validate_json_files(integration)