[C++]Expose API for pushing down rep/def level comparison down to decoder

[asfimport]

#6985 shows the benefit of using SIMD for level to bitmap conversion.  We can do even better by exploiting RLE runs when doing comparisons.  Exposing an appropriate API and using that would likely improve real world use-cases even further.

Reporter: Micah Kornfield / @emkornfield

_{Note: This issue was originally created as ARROW-8600. Please see the migration documentation for further details.}

[thisisnic]

This issue hasn't had activity in a long time. If it's still being worked on, please leave a comment. Otherwise, it will be closed on 23rd June.

Labelled Status: Stale-Warning for tracking.