[sqllogictest] Support pg_typeof

[melgenek]

Which issue does this PR close?

Closes #5147.

Rationale for this change

In sqllogictest tests I could write a query for Datafusion like this one

select arrow_typeof(null and null), arrow_typeof(null or null);

I would like to write the same query for Postgres, so that not only values are checked for compatibility but also types

select pg_typeof(null and null), pg_typeof(null or null);

What changes are included in this PR?

This pr includes handling of regtype results in Postgres sqllogictest client.

Are these changes tested?

Github actions

Are there any user-facing changes?

Sqllogictest only

[alamb]

Thanks @melgenek

[ursabot]

Benchmark runs are scheduled for baseline = 8bae10b and contender = b6dbb8d. b6dbb8d 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-datafusion-commits is not supported on ec2-t3-xlarge-us-east-2] ec2-t3-xlarge-us-east-2
[Skipped ⚠️ Benchmarking of arrow-datafusion-commits is not supported on test-mac-arm] test-mac-arm
[Skipped ⚠️ Benchmarking of arrow-datafusion-commits is not supported on ursa-i9-9960x] ursa-i9-9960x
[Skipped ⚠️ Benchmarking of arrow-datafusion-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