support: Date +/plus Int or date_add function

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

we have requirements related to the date operation, such as `date_add`, `date_sub`.

In the spark and mysql, the `date_add(start_date, value_expr)` function has been supported.
But in the datafusion, we only use the `expr + interval 'value' day` to support them.

In the mysql or the spark, the second args can be the expr, but the datafusion has no method to get the same target.

### Describe the solution you'd like

In the PG document, PG support `date +/plus integer`.

We can try to support this feature in the datafusion or in the kernel of arrow-rs.

### Describe alternatives you've considered

_No response_

### Additional context

cc @waitingkuo @alamb

Start by tracing DataFusion's handling of date expressions and interval arithmetic, then compare the requested date_add/date_sub behavior with PostgreSQL, Spark, and MySQL semantics. Determine whether support belongs in DataFusion or arrow-rs. Done means expression-valued date operations and date + integer behavior work consistently, with tests covering the requested forms.

Written by the indexing model from the issue text.