[Stats Page] - Add Ability to Graph Time Series Data

Description

Currently the create graph endpoint only supports creating graphs that are numerical values grouped by some category. We need the ability to display changes of data over time, like number of workpackages made over a period of time.

Acceptance Criteria

Able to graph values over time.

Proposed Solution

See how the group by selection was made. I assume well need to limit this functionality to the COUNT measure for now, then query all the items that are searched for in the graphGen element, then filter them by the start and end date, and create a map for each day or time period and see when the date created values are made to group them into those days.

Mocks

epic #2219

Start by tracing the Stats Page create graph endpoint and the existing group-by selection logic. Review how the graphGen element identifies searched items, then define the COUNT time-series behavior described in the proposal; done means the endpoint can graph values grouped by day or another time period within the selected start and end dates.