Allow entry of -90 & 90 degrees latitude

[robyngit]

A user recently encountered a limitation in the editor when attempting to input -90 degrees latitude. This restriction prevented the inclusion of the South Pole in their dataset, which was crucial as they had measurements from that area. The user resorted to using -89 degrees as a workaround. The decision to define -90 & 90 as invalid latitudes was based on a previous discussion (linked: #2159 (comment)), but this is too restrictive and 90 & -90 is valid EML. We should check that inclusion of the poles in the EML GeoCoverage does not have any negative consequences for the search and mapping, and fix these at the same time if needed.

[robyngit]

Search-wise, datasets that contain the north or south pole are assigned an appropriate geohash.

In Cesium, those geohashes are displayed correctly:

In the 2D Google maps, they aren't displayed very well:

I'll see if there's an easy workaround for this, but I suggest that we shouldn't spend a lot of time resolving this given that we are moving toward transitioning to Cesium.

[robyngit]

The limitation here seems to be with the Google Maps API. It seems that the imagery doesn't extend all the way to the poles. Among other parameters, I tried using different maptypes, but none worked. I propose that time is better spent using a different platform like Cesium to display static maps on the dataset landing pages. If we decide that that finding a resolution to the Google Maps display is needed, we should write up a new issue for that specific problem.