update the IceSat-2 R package (OpenAltimetry --> EarthData)

[mlampros]

I'll add information in this issue as I update the IceSat-2 R package after the migration of the OpenAltimetry to EarthData

• available_nominal_orbits (Nominal mission orbits)
• available_RGTs (Reference Ground Tracks (RGTs))
• degrees_to_global_grid (Create a global grid based on degrees)
• getTracks (Get the ICESAT-2 Tracks)
• get_atlas_data
• get_level3a_data(Get IceSat-2 ATLAS 'Level-3A' data for a time interval)
• latest_orbits (Extraction of the url from the Technical Specification Website)
• ne_10m_glaciated_areas (Natural Earth 10m Glaciated Areas (1:10 million scale))
• overall_mission_orbits (Overall Mission Orbits)
• revisit_time_RGTs (Revisit Time Reference Ground Tracks and Dates)
• RGT_cycle_14 Reference (Ground Tracks (RGTs) for IceSat-2 Cycle 14)
• select_aoi_global_grid (R6 Class to Select an Area of Interest (AOI) from a Global Grid)
• time_specific_orbits (Time Specific Orbits)
• verify_RGTs (Verification of the Reference Ground Tracks (RGTs))
• vsi_kml_from_zip (Utilizing Virtual File Systems (vsi) to extract the .kml from the .zip file)
• vsi_nominal_orbits_wkt (Utilizing Virtual File Systems (vsi) and Well Known Text (WKT) to access the 'nominal orbits')
• vsi_time_specific_orbits_wkt (Utilizing Virtual File Systems (vsi) and Well Known Text (WKT) to access the 'time specific orbits')

This issue is a continuation of #13

[mlampros]

The updated earthdata openaltimetry API (which the IceSat2R package uses) is available in the following weblink:
https://openaltimetry.earthdatacloud.nasa.gov/data/openapi/swagger-ui/index.html

[mlampros]

The interactive shiny application which allows the visualization and selection of grid cells requires the development version of leafgl (as of July 2024). The current CRAN version of "leafgl" which is 0.1.1 does not render the polylines and polygons as mentioned also here and here