Improve formatting of logical plans containing subqueries

[andygrove]

Which issue does this PR close?

Closes #2898

Rationale for this change

Before:

Projection: #employee_csv.id
  Filter: #employee_csv.state IN (Subquery: TableScan: employee_csv projection=[state])
    TableScan: employee_csv projection=[id, state]

After

Projection: #employee_csv.id
  Filter: #employee_csv.state IN (<subquery>)
    Subquery:
      TableScan: employee_csv projection=[state]
    TableScan: employee_csv projection=[id, state]

What changes are included in this PR?

• IndentVisitor visits all inputs, including subqueries
• Subquery expressions no longer display their subqueries

Are there any user-facing changes?

Yes, plans look different

[andygrove]

@avantgardnerio This might help simplify some of your tests

[andygrove]

This is the main change. We now visit all inputs, including subqueries. I have only implemented this for Projection and Filter in this PR.

[codecov-commenter]

Codecov Report

Merging #2899 (7592829) into master (6a5de4f) will decrease coverage by 0.00%.
The diff coverage is 82.25%.

❗ Current head 7592829 differs from pull request most recent head 37ab28a. Consider uploading reports for the commit 37ab28a to get more accurate results

@@            Coverage Diff             @@
##           master    #2899      +/-   ##
==========================================
- Coverage   85.34%   85.34%   -0.01%     
==========================================
  Files         276      276              
  Lines       49294    49322      +28     
==========================================
+ Hits        42071    42092      +21     
- Misses       7223     7230       +7     

Impacted Files	Coverage Δ
datafusion/expr/src/expr.rs	83.60% <0.00%> (-2.50%)	⬇️
datafusion/optimizer/src/filter_push_down.rs	98.23% <ø> (ø)
datafusion/optimizer/src/limit_push_down.rs	99.67% <ø> (ø)
...atafusion/optimizer/src/subquery_filter_to_join.rs	93.90% <ø> (ø)
datafusion/expr/src/logical_plan/plan.rs	76.20% <95.23%> (+1.64%)	⬆️
datafusion/expr/src/logical_plan/builder.rs	89.86% <100.00%> (ø)
datafusion/sql/src/planner.rs	81.31% <100.00%> (-0.07%)	⬇️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 6a5de4f...37ab28a. Read the comment docs.

[avantgardnerio]

This looks very helpful!

[alamb]

Nice

[ursabot]

Benchmark runs are scheduled for baseline = 6a5de4f and contender = fd64e6f. fd64e6f 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