Is your feature request related to a problem or challenge? Please describe what you are trying to do.
Arrow has added REE support apache/arrow#14176, similar to dictionary arrays that allow repeated values to be encoded in a space efficient manner that also allows fast processing.

Describe the solution you'd like
Implement REE in arrow-rs. Some likely candidate:

• Support in DataType
• Support in ArrayData
• New REE array
• Support REE in IPC
• Support REE in cast kernels
• Support REE in compute kernels

Describe alternatives you've considered
Remaining tasks:

• arrow-row: Add support for REE #7649
• arrow-select: Implement concat for RunArrays #7487
• arrow-data: Add REE support for build_extend and build_extend_nulls #7671
• Implement PartialEq for RunArray #7691
• Reduce repetition in tests for arrow-row/src/run.rs #7692
• Improve performance of RunArray --> Row conversion #7693
• Potential Optimization for interleave/take on RunEndEncoded arrays #7710
• Implemented casting for RunEnd Encoding #7713

Additional context

Among other things, @brancz is working to improve aggregation performance in DataFusion using Runarrays, see

• Support Aggregating by RunArrays datafusion#16011