Finalize run-end-encoding support

After #507 we have REE support! There are a few places this still needs to be integrated:

- Integration tests
- R bindings
- Python bindings
- Potentially a helper for iterating along it or resolving an element out of it (e.g., using a binary search). This might also be combined with a helper for dictionary arrays to help consumers support a wider variety of the new encodings

Also, we should review the C++ implementation for more utilities/gotchas/cases we need to ensure validate (or fail to validate) as per https://github.com/apache/arrow-nanoarrow/pull/507#issuecomment-2155325414

https://github.com/apache/arrow/blob/main/cpp/src/arrow/util/ree_util.h
and
https://github.com/apache/arrow/blob/main/cpp/src/arrow/util/ree_util.cc
are good sources to look at.

Start by reviewing the REE implementation from #507 and the reference files arrow/util/ree_util.h and arrow/util/ree_util.cc. Then inspect the integration tests plus the R and Python bindings to identify the remaining support work. Done means those integrations are covered and the C++ validation, utilities, and edge cases have been reviewed.

Written by the indexing model from the issue text.