[Core] Add Layer Lock feature (#23430)

Co-authored-by: Daniel <1767914+iamdanielv@users.noreply.github.com>
Co-authored-by: Pascal Getreuer <getreuer@google.com>
Co-authored-by: Pascal Getreuer <50221757+getreuer@users.noreply.github.com>

data/schemas/keyboard.jsonschema

@@ -375,6 +375,12 @@
             }
         },
         "keycodes": {"$ref": "qmk.definitions.v1#/keycode_decl_array"},
+        "layer_lock": {
+            "type": "object",
+            "properties": {
+                "timeout": {"$ref": "qmk.definitions.v1#/unsigned_int"}
+            }
+        },
         "layout_aliases": {
             "type": "object",
             "additionalProperties": {"$ref": "qmk.definitions.v1#/layout_macro"}