Reservoirs and Observation Site Shiny App: Add interactive count of sites

[amabdallah]

Need: Add interactive count of sites
Why? We need to help users see how many sites are there that meet the selected filters' criteria. e.g., how many sites are there that measure reservoir level/storage across the West? or just in UT. How many sites are there that measure surface water flow across the West?

https://waterdataexchangewswc.shinyapps.io/SiteSpecificReservoirAndObservationSiteDemo/

[rwjam]

Added a small renderText() output that is counting the number of unique SiteUUID entries within the dataframe. Adjusts for filters.

Looks like the vast majority of our sites for ssro are in Colorado.

[amabdallah]

@rwjam Nice work! As a next step, I think it would be super helpful if you make the legend dynamic based on the site type. That would help us better tell the story of these sites.