Replace the way Geographic Coordinate Reference System are stored in an iModel.

[AlainRobertAtBentley]

Currently the definition of a Geographic Coordinate Reference System is stored in an iModel using a semi-opaque binary structure. It should be instead stored as a JSON fragment for two reasons:
A - The JSON fragment is open and easily (so to speak) understandable by a human
B - The JSON fragments support definition details that are not supported by the binary structure (such as additional transforms) meaning people can create an iModel and try to set a GCRS that cannot be stored in the iModel.

Of course, support of the binary for reading is essential for older iModels.