Add ability to upload a ROI in geoJSON format

[dbuscombe-usgs]

Like CoastSeg, we should be able to upload a geojson polygon file specifying ROI

[2320sharon]

I'll be adding an additional button that lets the user load a regular geojson file containing ROIs

• [x] Add load geojson file button
• [x] Add function similar to coastseg to load ROIs on the map
• [x] Convert user's crs to map crs of epsg:4326