Fix unspecified-encoding warnings in tests (#119405)

tests/common.py

tests/components/blueprint/test_importer.py

tests/components/blueprint/test_websocket_api.py

tests/components/color_extractor/test_service.py

tests/components/folder/test_sensor.py

tests/components/google_assistant/test_http.py

tests/components/kira/test_init.py

tests/components/recorder/common.py

tests/components/recorder/test_statistics_v23_migration.py

tests/helpers/test_storage.py

tests/test_block_async_io.py

tests/test_config.py

tests/test_core.py

tests/util/test_file.py

tests/util/test_json.py