Gate dyn comparison of dictionary arrays behind dyn_cmp_dict

[tustvold]

Which issue does this PR close?

Closes #2596

Rationale for this change

See ticket, improves release compilation times by ~50%.

With dictionary comparison kernels

________________________________________________________
Executed in   84.84 secs    fish           external
   usr time  227.45 secs  662.00 micros  227.44 secs
   sys time    6.23 secs  131.00 micros    6.23 secs

Without dictionary comparison kernels

________________________________________________________
Executed in   21.45 secs    fish           external
   usr time  154.13 secs    0.00 micros  154.13 secs
   sys time    6.24 secs  880.00 micros    6.24 secs

What changes are included in this PR?

Adds a new dyn_cmp_dict feature flag. I opted to not enable this by default as I think the rarity of people relying on this functionality, combined with the significant bloat reduction I think warrants a breaking change.

Are there any user-facing changes?

Yes

[ursabot]

Benchmark runs are scheduled for baseline = 86446ea and contender = 6ab208c. 6ab208c is a master commit associated with this PR. Results will be available as each benchmark for each run completes.
Conbench compare runs links:
[Skipped ⚠️ Benchmarking of arrow-rs-commits is not supported on ec2-t3-xlarge-us-east-2] ec2-t3-xlarge-us-east-2
[Skipped ⚠️ Benchmarking of arrow-rs-commits is not supported on test-mac-arm] test-mac-arm
[Skipped ⚠️ Benchmarking of arrow-rs-commits is not supported on ursa-i9-9960x] ursa-i9-9960x
[Skipped ⚠️ Benchmarking of arrow-rs-commits is not supported on ursa-thinkcentre-m75q] ursa-thinkcentre-m75q
Buildkite builds:
Supported benchmarks:
ec2-t3-xlarge-us-east-2: Supported benchmark langs: Python, R. Runs only benchmarks with cloud = True
test-mac-arm: Supported benchmark langs: C++, Python, R
ursa-i9-9960x: Supported benchmark langs: Python, R, JavaScript
ursa-thinkcentre-m75q: Supported benchmark langs: C++, Java

[alamb]

Can we possibly document this new flag in https://github.com/apache/arrow-rs/blob/master/arrow/README.md#feature-flags ?