Implement Spark-compatible cast to/from binary type

[andygrove]

What is the problem the feature request solves?

#362 added some tests for casting to/from binary. Some pass and some are ignored because they currently fail.

This issue is for investigating the failures and either adding documentation to explain why we are incompatible, or making them compatible.

Describe the potential solution

No response

Additional context

No response

[mattharder91]

I would like to work on this

[andygrove]

Thanks @mattharder91. Feel free to break this down into smaller issues if needed e.g. string <-> binary, integers <-> binary and so on.

There is a little more info on binary -> string in #379. It looks this works for valid UTF-8 inputs but Spark allows non UTF-8 input.