Wire up with_new_state with DataSource (#20718)

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- Closes #.

## Rationale for this change

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`ExecutionPlan::with_new_state()` allows devs to inject custom
information in their nodes that they can use for tweaking their
`ExecutionPlan` implementations.

This mechanism does not work today if the `ExecutionPlan` is a
`DataSourceExec`, as this one does not implement the `with_new_state()`
method from `ExecutionPlan`.

In order to let people use this also for their own `DataSource`
implementations, this PR adds this method to it.

## What changes are included in this PR?

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PR.
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Propagates `with_new_state()` to the `DataSource` trait, so that custom
`DataSourceExec` can also benefit from it.

## Are these changes tested?

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As it's just method plumbing, my impression is that having a test for it
is overkill.

## Are there any user-facing changes?

Users can now implement their `with_new_state()` also in `DataSource`,
not only in `ExecutionPlan`

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Author: gabotechs

datafusion/datasource/src/source.rs

@@ -228,6 +228,22 @@ pub trait DataSource: Send + Sync + Debug {
         &self,
         f: &mut dyn FnMut(&dyn PhysicalExpr) -> Result<TreeNodeRecursion>,
     ) -> Result<TreeNodeRecursion>;
+
+    /// Injects arbitrary run-time state into this DataSource, returning a new instance
+    /// that incorporates that state *if* it is relevant to the concrete DataSource implementation.
+    ///
+    /// This is a generic entry point: the `state` can be any type wrapped in
+    /// `Arc<dyn Any + Send + Sync>`.  A data source that cares about the state should
+    /// down-cast it to the concrete type it expects and, if successful, return a
+    /// modified copy of itself that captures the provided value.  If the state is
+    /// not applicable, the default behaviour is to return `None` so that parent
+    /// nodes can continue propagating the attempt further down the plan tree.
+    fn with_new_state(
+        &self,
+        _state: Arc<dyn Any + Send + Sync>,
+    ) -> Option<Arc<dyn DataSource>> {
+        None
+    }
 }
 
 /// [`ExecutionPlan`] that reads one or more files
@@ -432,6 +448,18 @@ impl ExecutionPlan for DataSourceExec {
                     as Arc<dyn ExecutionPlan>
             })
     }
+
+    fn with_new_state(
+        &self,
+        state: Arc<dyn Any + Send + Sync>,
+    ) -> Option<Arc<dyn ExecutionPlan>> {
+        self.data_source
+            .with_new_state(state)
+            .map(|new_data_source| {
+                Arc::new(self.clone().with_data_source(new_data_source))
+                    as Arc<dyn ExecutionPlan>
+            })
+    }
 }
 
 impl DataSourceExec {