Reorganized layout of CI directory, move all before_install files into

common directory, remove copy-pasted files

CI/validate_json.py

@@ -0,0 +1,28 @@
+#!/usr/bin/env python3
+
+import re
+import sys
+from pathlib import Path
+from pprint import pprint
+
+# VCMI supports JSON with comments, but not JSON5
+import jstyleson 
+
+validation_failed = False
+
+for path in sorted(Path(".").glob("**/*.json"), key=lambda path: str(path).lower()):
+    # because path is an object and not a string
+    path_str = str(path)
+    if path_str.startswith("."):
+        continue
+
+    try:
+        with open(path_str, "r") as file:
+            jstyleson.load(file)
+        print(f"✅ {path_str}")
+    except Exception as exc:
+        print(f"❌ {path_str}: {exc}")
+        validation_failed = True
+
+if validation_failed:
+    sys.exit(1)