Add `auto_explain` mode

### Is your feature request related to a problem or challenge?

It would be useful to collect plans from queries automatically, without needing to explicitly add `EXPLAIN ANALYZE`. This would ensure that the original application would not need to change, as the queries would still return data as normal, while the plans would be printed to `stdout`/`stderr`.

Some existing systems already support this feature, like [`auto_explain`](https://www.postgresql.org/docs/18/auto-explain.html) in Postgres and [`eqp`](https://www.sqlite.org/eqp.html) in SQLite.

### Describe the solution you'd like

Some `datafusion.execution.auto_explain` config that would enable this feature.

I already created a small proof of concept and this feature would be relatively easy to implement. We just need to wrap execution plans in an `AnalyzeExec`. This `AnalyzeExec` would also need a flag to know when it's in the `auto_explain` mode, in which case it would print the plans and return the input batches.

I would be happy to create a PR with this.

### Describe alternatives you've considered

Adding `EXPLAIN ANALYZE` manually, but this changes the application.

### Additional context

_No response_

Start by reviewing AnalyzeExec and the execution-plan path, then locate where datafusion.execution configuration is defined. Done means an auto_explain setting collects and prints plans while returning query data normally, without requiring application queries to change.

Written by the indexing model from the issue text.