KUDU-3353 [schema] Support to modify immutable attribute on column schema

In the previous implementation of adding immutable attribute
to column on C++ client side ec3a9f75b6924a70ecbf08e3805228ad9b92b9f0,
it missed to alter column schema to add/remove immutable attribute.

This patch implements it and adds some tests.

Change-Id: I213957bfb3a87b8e1a92cfd340a2e806d192f9ba
Reviewed-on: http://gerrit.cloudera.org:8080/18996
Reviewed-by: Alexey Serbin <alexey@apache.org>
Tested-by: Alexey Serbin <alexey@apache.org>
8 files changed