Update tests (#618)

This exercises all the API functions, unlike the original, which only
run a few. It might be best to use `View File` to see
`python_api_tests.py`. (I didn't even look at the diff.)

tests/dataset/data.csv

@@ -0,0 +1,6 @@
+id, fruit
+1, apple
+2, banana
+3, citrus
+4, apple
+5, durian

tests/kernel/testing.ipynb

@@ -0,0 +1 @@
+{"metadata":{"kernelspec":{"language":"python","display_name":"Python 3","name":"python3"},"language_info":{"name":"python","version":"3.10.13","mimetype":"text/x-python","codemirror_mode":{"name":"ipython","version":3},"pygments_lexer":"ipython3","nbconvert_exporter":"python","file_extension":".py"},"kaggle":{"accelerator":"none","dataSources":[],"dockerImageVersionId":30646,"isInternetEnabled":true,"language":"python","sourceType":"notebook","isGpuEnabled":false}},"nbformat_minor":4,"nbformat":4,"cells":[{"cell_type":"code","source":"# This Python 3 environment comes with many helpful analytics libraries installed\n# It is defined by the kaggle/python Docker image: https://github.com/kaggle/docker-python\n# For example, here's several helpful packages to load\n\nimport numpy as np # linear algebra\nimport pandas as pd # data processing, CSV file I/O (e.g. pd.read_csv)\n\n# Input data files are available in the read-only \"../input/\" directory\n# For example, running this (by clicking run or pressing Shift+Enter) will list all files under the input directory\n\nimport os\nfor dirname, _, filenames in os.walk('/kaggle/input'):\n    for filename in filenames:\n        print(os.path.join(dirname, filename))\n\n# You can write up to 20GB to the current directory (/kaggle/working/) that gets preserved as output when you create a version using \"Save & Run All\" \n# You can also write temporary files to /kaggle/temp/, but they won't be saved outside of the current session","metadata":{"_uuid":"8f2839f25d086af736a60e9eeb907d3b93b6e0e5","_cell_guid":"b1076dfc-b9ad-4769-8c92-a6c4dae69d19","execution":{"iopub.status.busy":"2024-06-11T17:18:41.771461Z","iopub.execute_input":"2024-06-11T17:18:41.771892Z","iopub.status.idle":"2024-06-11T17:18:43.04124Z","shell.execute_reply.started":"2024-06-11T17:18:41.771858Z","shell.execute_reply":"2024-06-11T17:18:43.03999Z"},"trusted":true},"execution_count":null,"outputs":[]}]}

tests/model/instance/data.csv

@@ -0,0 +1,6 @@
+id, fruit
+1, apple
+2, banana
+3, citrus
+4, apple
+5, durian

tests/model/instance/version/metadata.json

@@ -0,0 +1 @@
+{}