[Format][C++] Add "LargeMap" type with 64-bit offsets

It would be nice if a "LargeMap" type existed along side the "Map" type for parity. For other datatypes that require offset arrays/buffers, such as String, List, BinaryArray, provides a "large" version of these types, i.e. LargeString, LargeList, and LargeBinaryArray. It would be nice to have a "LargeMap" for parity.