graph_prediction_vs_actual_over_time supports visualizing multiseries time series performance.

[MichaelFu512]

Description

As a user and developer of multiseries time series in EvalML, I would like our graph_prediction_vs_actual_over_time function to support visualizing multiseries time series performance.

There are two options for how to update the function:

• An argument passed in to the function delineating which single series of the multiseries dataset to plot
• The function automatically generates separate plot for each dataset
• 1 & 2 combined, the function will automatically plot all series, unless a single series is passed in in which case it will plot only the one

Acceptance Criteria (AC)

• graph_prediction_vs_actual_over_time takes in stacked data
• graph_prediction_vs_actual_over_time provides the option to visualize multiseries problems, as described above

Jira link (TML-8241)

https://alteryx.atlassian.net/browse/TML-8241