[C++] Deprecate ArrayBuilder::Advance?

[Antoine Pitrou]

Hello,

It seems ArrayBuilder::Advance has never been terribly useful, since the 
user has no obvious way of getting data pointers to the various 
underlying buffers.  Furthermore, it's almost untested and potentially 
buggy (see https://issues.apache.org/jira/browse/ARROW-14065).

I therefore propose that we deprecate ArrayBuilder::Advance.  Users who 
want sophisticated control over array creation can instead use the 
various BufferBuilder facilities directly.

Regards

Antoine.