Adding "Task Consumption" column on each workflow

I hope we can get a stats page, a column in the workflow list page and history runs page, showing how much task is consumed by every workflow.

On the stats page, it should show us in a graph with time range on x-axis.
On the workflow list page, it should show the accrued task usage for the current billing month.
On the historic run page, it should show the task usage every pieces (this really when we need to check usages on loops / recursive loops)