fix: panic in ListingTableFactory when session is not SessionState

[evangelisilva]

Which issue does this PR close?

• Closes Potential panic due to unchecked downcast in ListingTableFactory::create #20113.

Rationale for this change

This PR fixes a potential panic in ListingTableFactory::create when the provided Session instance is not a SessionState.

Previously, the code used .unwrap() on downcast_ref::<SessionState>(). If a custom Session implementation was used (which is allowed by the trait), this would cause a crash. This change replaces .unwrap() with ok_or_else, returning a proper DataFusionError::Internal instead.

What changes are included in this PR?

• Replaced .unwrap() with ok_or_else in ListingTableFactory::create to safely handle session downcasting.
• Added a regression test test_create_with_invalid_session in datafusion/core/src/datasource/listing_table_factory.rs that uses a MockSession to verify the error is returned instead of panicking.

Are these changes tested?

Yes.

• Added new unit test test_create_with_invalid_session.
• Ran cargo test -p datafusion --lib datasource::listing_table_factory::tests::test_create_with_invalid_session and it passed.

Are there any user-facing changes?

No.

[alamb]

Thank you @evangelisilva -- this looks good to me

[alamb]

this test is probably overkill, but it isn't a terrible thing to have coverage

[alamb]

I ran cargo fmt to resolve the CI run and merged up from main