run.log_table stores 1-item lists differently

The following code:
```
run.log_table('test',value={'x':['asd','sdf'],'y':[1,2]})
run.log_table('test1',value={'x':['asd'],'y':[1]})
run.get_metrics()
```
will yield:
`{'test': {'x': ['asd', 'sdf'], 'y': [1, 2]}, 'test1': {'x': 'asd', 'y': 1}}`

It shows that single-item lists are stored differently than lists with multiple items.

This makes the JSON produced from these inconsistent types hard to parse down the line (e.g. outside of AML as in PowerBI for example).

If we pass in a list, we would expect that it is stored as a list even if there is only one item in the list.

---
#### Document Details

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* ID: 2e24ac95-7027-6a3c-81e6-f20cc4415219
* Version Independent ID: 9498cdc2-0d04-39a3-08ce-ef9ea8f2d153
* Content: [azureml.core.run.Run class - Azure Machine Learning Python](https://docs.microsoft.com/en-us/python/api/azureml-core/azureml.core.run.run?view=azure-ml-py)
* Content Source: [AzureML-Docset/stable/docs-ref-autogen/azureml-core/azureml.core.run.Run.yml](https://github.com/MicrosoftDocs/MachineLearning-Python-pr/blob/live/AzureML-Docset/stable/docs-ref-autogen/azureml-core/azureml.core.run.Run.yml)
* Service: **machine-learning**
* Sub-service: **core**
* GitHub Login: @debfro
* Microsoft Alias: **debfro**

Comienza reproduciendo las llamadas proporcionadas a Run.log_table y Run.get_metrics en el contexto del Azure Machine Learning Python SDK. Traza cómo se representan las listas de un solo elemento en las métricas y el JSON devueltos; después, añade cobertura que demuestre que las listas de un solo elemento pasadas explícitamente siguen siendo listas.

Escrito por el modelo de indexación a partir del texto del issue.