Specify requirements and design for data visualization of historic trends

[ruckeralex]

This is for down the road, but we will need to specify requirements, design, and any missing pieces for future more sophisticated data visualization of historic trends of the unsafe drinking water in water systems. This should build off of the visualization work done by @r-b-g-b that contributed to winning the 2018 California Water Data Challenge!

We want to be able to provide an attractive, accessible, usable way for the analysts and residents to analyze the data to see the duration, frequency, and magnitude of exceedance events for a given CWS and Service Area's affected population, and for trends by region, by analyte, and by time period.

The SWRCB staff shared the attached image to sketch out potential interactive visual reporting... users could scroll to right and left to see violations for unsafe water, by agency and for all agencies, in more and less recent years.

[ruckeralex]

@nayanab565 - feel free to jump into this task! You can identify data visualizations that you like and apply them to the data!