The get_range_to_endpoint_map method, takes a keyspace and returns a map
between the token ranges and the endpoint.
It is used by some external tools for repair.
Token ranges are codes as size-2 array, if start or end are empty, they will be
added as an empty string.
The implementation uses get_range_to_address_map and re-pack it
accordingly.
The use of stream_range_as_array it to reduce the risk of large
allocations and stalls.
Relates to scylladb/scylla-jmx#36
Signed-off-by: Amnon Heiman <amnon@scylladb.com>
Closes#7329