Replace `Box`es with `Arc` in the `Expr` `enum`.

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

_No response_

### Describe the solution you'd like

According to following stackoverflow [discussion](https://stackoverflow.com/a/76403415/10554257). `Box`s can deep copy when called with `.clone()` method (according to `.clone()` implementation of the underlying type.).

For `Box` this is the case. I think this usage might be the reason of some deep stack usages seen during the planning.

See related issues: [#9375](https://github.com/apache/arrow-datafusion/issues/9375), [#8837](https://github.com/apache/arrow-datafusion/issues/8837).

I think, replacing `Box` usages with `Arc` under the `enum Expr` would improve performance. I am not familiar with the implications of these two approaches in other places. I wonder what community thinks about this change. Would it be better, unnecessary, etc?

### Describe alternatives you've considered

_No response_

### Additional context

_No response_

Start with the Expr enum and its Box usages, then read related issues #9375 and #8837 and the linked Stack Overflow discussion. Identify the implications of replacing these boxes with Arc across callers and tests; done would require an agreed design and evidence that the change improves the reported stack usage without breaking behavior.

Written by the indexing model from the issue text.