[Substrait] ReadRel. Get column names from TableScan source

[andygrove]

Which issue does this PR close?

Part of #4897

Original PR in datafusion-substrait repo: datafusion-contrib/datafusion-substrait#37

Rationale for this change

Quick fix to list ALL columns from source table in ReadRel base_schema.

According to Substrait documentation, the base_schema (Direct Schema) property should contain all columns BEFORE projection or emit/hiding is applied.

What changes are included in this PR?

Are these changes tested?

No .. this is applying a PR that was already merged in the original repo prior to us accepting the code donation here, so I am just trying to get those changes re-applied

Are there any user-facing changes?

[andygrove]

@nseekhao fyi

[alamb]

Looks reasonable to me

[ursabot]

Benchmark runs are scheduled for baseline = 3f5b834 and contender = e30711d. e30711d 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