Implement tree explain for ProjectionExec

[alamb]

Is your feature request related to a problem or challenge?

• Part of [EPIC] Complete SQL EXPLAIN Tree Rendering #14914

@irenjj added a new tree explain mode in #14677. Now we need to add support for different types of operators.

Here is an example of how to see the new explain plans:

set datafusion.explain.format = 'tree';
create table foo(x int, y int) as values (1,2), (3,4);
explain select * from foo where x = 4;
+---------------+------------------------------------+
| plan_type     | plan                               |
+---------------+------------------------------------+
| logical_plan  | Filter: foo.x = Int32(4)           |
|               |   TableScan: foo projection=[x, y] |
| physical_plan | ┌───────────────────────────┐      |
|               | │    CoalesceBatchesExec    │      |
|               | └─────────────┬─────────────┘      |
|               | ┌─────────────┴─────────────┐      |
|               | │         FilterExec        │      |
|               | └─────────────┬─────────────┘      |
|               | ┌─────────────┴─────────────┐      |
|               | │       DataSourceExec      │      |
|               | │    --------------------   │      |
|               | │    partition_sizes: [1]   │      |
|               | │       partitions: 1       │      |
|               | └───────────────────────────┘      |
|               |                                    |
+---------------+------------------------------------+

Describe the solution you'd like

Add tree format to the ExecutionPlan specified in the subject of this ticket

Note that the tree mode should have only the most relevant information for users to understand what plan is being run. Detailed iformation

The process goes like:

1. Add the relevant code to the operator
2. Add / update explain_tree.slt test to show the new code in action

The relevant code looks like this

            DisplayFormatType::TreeRender => {
                // TODO: collect info
                write!(f, "")?;
            }

You can run the tests like

cargo test --test sqllogictests -- explain_tree

You can update the test like this:

cargo test --test sqllogictests -- explain_tree --complete

Describe alternatives you've considered

Here is an example PR that shows what is needed

• Implement tree explain for FilterExec #15001

Additional context

Since this is well specified and has several examples and will give exposure to DataFusion code and testing, I have marked this as a good first issue

[Elctrony]

Take

[Elctrony]

Can I DM one of the mentors regarding this issue?

[alamb]

Can I DM one of the mentors regarding this issue?

In general, development on DataFusion happens following the Apache Way, that is in the open as much as possible. If you have a question, perhaps you can ask it here on the ticket and we'll find community feedback