Use the chart type as a default chart title

[lindseywild]

Is your feature request related to a problem? Please describe.
In #2732, titles and descriptions will be added to each chart and chart type. We want to ensure that the default title text at least gives the user an idea of what the chart is (i.e. here: #2904).

Describe the solution you'd like
Add the title type to the fallback title text.

Once concern is that some of the titles are visible on charts if they're filled out. If we were to add a fallback, it would apply visible titles to all charts, which would be a breaking change to some users.