Add Size Variable option to Time Series Graphs

[shane-kercheval]

For example, perhaps I'm graphing by Count (e.g. per month) and want to size points by total (or mean?median?) value

Or perhaps I'm graphing by total value, and want to size points by the number of records in each cohort.

Would have different options whether Numeric Aggregation was selected. If not selected, we are doing count and it is an example of the former, where I would also need to ask user what the size should be based on (total/mean/median). If selected, I'm guessing the only option I should provide is "by Count".