Optimize the evaluation of `DATE_TRUNC(<col>) == <constant>)` when pushed down

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

Filing on behalf of @colinmarc and @drin so we can get more community help

It is much easier for table providers such as the build in parquet one as well as iceberg to push down ` op ` expressions. They often don't push the predicates down if they have a scalar function wrapping them

For example using the predicate
```sql
date_trunc(part, column) <= constant_rhs
```
Will not typically be able to be pushed down

However, this equivalent expression can be
```sql
column <= date_trunc(part, date_add(constant_rhs, INTERVAL 1 part)
```

### Describe the solution you'd like

It would be good if DataFusion could do this type of rewrite

### Describe alternatives you've considered

This seems to fit well into the existing simply expressions framework:
https://github.com/apache/datafusion/tree/main/datafusion/optimizer/src/simplify_expressions

And we already do something very similar for casts in unwrap casts: https://github.com/apache/datafusion/blob/e12ef3ae90677fe4b1bc548feea2b3082eecdaa2/datafusion/optimizer/src/simplify_expressions/unwrap_cast.rs#

For example
```sql
CAST(x AS float) = 5
```
is rewritten to
```sql
x = CAST(5 as float)
```
The code for that is here:

Perhaps we can follow a similar model for date_trunc

Note There is already a [`ScalarUDFImpl::simplify`](https://docs.rs/datafusion/latest/datafusion/logical_expr/trait.ScalarUDFImpl.html#method.simplify) for simplifying functions, however that method doesn't get any part of the larger expression (the `=` in the above code) so we might have to extend the API somewhat

### Additional context

_No response_