This ticket is to unify naming throughout the sharding global indexes work. It will also change usages of ShardVersion to ChunkVersion where needed. For the global indexes work, we have the following naming scheme as a plan:

IndexVersion ==> the timestamp telling when the last modification to global indexes was made

CollectionIndexes ==> an object containing both the IndexVersion and the collectionUUID

GlobalIndexesInfo ==> a structure holding the CollectionIndexes + the set of indexes for a collection

OptionalGlobalIndexesInfo ==> a struct with an optional GlobalIndexesInfo to be stored in the catalog cache

_indexCache ==> the portion of the catalog cache relating to global indexes.

Additionally after SERVER-71252 there is a way to distinguish between global and non-global indexes in the cache, however, the overall API is globalness agnostic, meaning we could be storing a regular index metadata in the catalog and the API would work the same, so actually we could rename the entire thing to not have the word 'global' in it.