CSFLE: implement mongo_csfle_v1_get_version_str and mongo_csfle_v1_get_version

mongo_csfle_v1_get_version_str and mongo_csfle_v1_get_version are declared in mongo_csfle.h, but appear unimplemented.

To reproduce, I downloaded the mongo_csfle_v1.dylib from the csfle_create_lib task and checked with nm:

nm ./mongo_csfle_v1.dylib | grep mongo_csfle_v1_get_version

nm ./mongo_csfle_v1.dylib| grep mongo_csfle_v1_get_version_str