Make `FromTableRow` a publicly exported trait

[abhiaagarwal]

As I was working on adding additional tests, I found this in the test-utils feature

etl/etl/src/test_utils/materialize.rs

Lines 6 to 15 in 3d08fd7

	pub trait FromTableRow: Sized {
	/// The type used to identify this record (usually an ID field)
	type Id: Eq + Clone;
	/// Convert a TableRow into this type, returning None if conversion fails
	fn from_table_row(table_row: &TableRow) -> Option<Self>;
	/// Get the identifier for this record (used for updates/deletes)
	fn id(&self) -> Self::Id;
	}

This would be super nice to be part of etl's public API, so destinations can use it to avoid defining their own traits. I'd also want to include a FromTableRowBatch trait, since in arrow-land, the columnar data model makes dealing with single rows memory-inefficient.

Happy to open an MR if think this would be an okay addition :)

[iambriccardo]

Hey, sorry about the delay! This trait was added only for testing purposes, it’s not actually needed in the public ETL API. Could you share a bit more about your use case and why you think such a trait would be useful?