Convert TrialResult to DataFrame

## Description

[TrialResult](https://docs.microsoft.com/dotnet/api/microsoft.ml.automl.trialresult?view=ml-dotnet-preview) gives you important information about each trial AutoML runs as part of an experiment. Although today we have the NotebookMonitor for real-time visualizations and feedback during training, once training is done, to get similar information, users have to write their own code to access each of these pieces of information.

## Proposal

Given an AutoML experiment called `experiment`, when training is done, users should be able to call `ToDataFrame` to convert the results of an AutoML experiment into a `DataFrame`.

```csharp
TrialResult experimentResults = await experiment.RunAsync();
DataFrame results = experimentResults.ToDataFrame();
```

The result should display columns with information for each of the trials in a DataFrame similar to the following:

| TrialId | DurationInMilliseconds | Metric | Pipeline | Parameter |
| --- | --- | --- | --- | --- |
| 21 | 8.5 | 0.98 | ... | ... |
| 5 | 3.8 | 0.83 | ... | ... |

From there, if users to sort / query the results using the built-in DataFrame methods, they can. Additionally, they can export to CSV using the [WriteCsv](https://docs.microsoft.com/en-us/dotnet/api/microsoft.data.analysis.dataframe.writecsv?view=ml-dotnet-preview) method.