registry (NEW): Icosahedral Snyder Equal Area a9 Rhombic 2DTMS

[jerstlouis]

Registration of the ISEA9R 2DTMS, as developed during the OGC FMSDI Phase 3 Pilot ( see https://docs.ogc.org/per/23-010.html#_a_two_dimensional_tile_matrix_set_based_on_isea9r ) in collaboration with @perrypeterson, @mpadillaruiz and @shatzi , and presented at the Singapore meeting in October 2022 (to the special marine session, as well as the DGGS and OGC API - Tiles SWG).

Making this a draft PR as the referenced CRS URI [OGC:153456] is not yet registered.

Attached are draft definitions in PROJJSON for the CRS of the 2DTMS as well as the OGC:1534 planar ISEA projection it is derived from:
isea56.json
isea.json

We could potentially embed the CRS in the 2DTMS "crs" object as this is allowed by the standard, but these registrations also depend on the registration of an ISEA operation method, as well as parameters for this method for the first vertex latitude, longitude and azimuth to second vertices.

So not sure if we could register this before these methods, parameters and CRSs are defined and update it afterwards?

Since the initial version, I have corrected the cellSizes to be in the CRS units, and also improved the accuracy of the scale denominators.

cc. @ldesousa