[client] KUDU-2671 move KuduRangePartition out of KuduTableCreator

This patch moves the KuduRangePartition class out of the
KuduTableCreator class.  The reasoning behind this change is two-fold:
  * make the API of KuduTableAlterer more consistent with the added
    AddRangePartition(KuduRangePartition* partition) method
  * avoid issues with embedded classes while cythonizing C++ client API
    while adding support for range-specific hash schemas

This change might break ABI compatibility, but we haven't announced
support for range-specific hash schemas in Kudu 1.16 since it was not
ready yet.  Any Kudu C++ client application that started using that
experimental API (which is very unlikely) should be recompiled with
updated headers and the kudu_client library.

Change-Id: I5af14e7e802baca496e13e05860d66685914dd29
Reviewed-on: http://gerrit.cloudera.org:8080/18765
Reviewed-by: Abhishek Chennaka <achennaka@cloudera.com>
Reviewed-by: Mahesh Reddy <mreddy@cloudera.com>
Tested-by: Alexey Serbin <alexey@apache.org>
Reviewed-by: Attila Bukor <abukor@apache.org>
7 files changed