[C++][Parquet] ompatibility with C++ iterators

[asfimport]

There are some places where it would clean up the code quite a bit to use C++ STL iterators and be compatible with their APIs.

Additionally, in this PR (apache/parquet-cpp#403) I had to allocate a separate vector to hold byte swapped values, when what I really want to do is iterate over the existing values in reverse (starting at the last valid byte) so I don't have to copy them into a separate container. This can be done with a std::reverse_iterator which allows one to use the ++ operator everywhere.

Reporter: Phillip Cloud / @cpcloud

_{Note: This issue was originally created as PARQUET-1159. Please see the migration documentation for further details.}

[asfimport]

Antoine Pitrou / @pitrou:
@cpcloud  Are you still willing to work on this?

[asfimport]

Phillip Cloud / @cpcloud:
I don't have the time to work on this. Better to close it than to keep kicking it to the next release.