Keep the id in an include's temp table when the queried document has duplicated fields (#5650)

[Blackclaws]

Fixes #5650.

An Include() joined on the queried document's own id failed with 42703: column d.id does not exist in a query session whenever the queried document had a duplicated field. The include's temp table was built from the DuplicatedFieldSelectClause, which a query session builds without the id column.

Change

TemporaryTableStatement already swaps a query session's select clause for one that carries the id. It now does the equivalent for a DuplicatedFieldSelectClause, calling EnsureColumn("d.id"). That's the same mechanism LINQ joins already use for their key column (EnsureJoinKeyInCte). In the other session kinds the id is already selected, so the call does nothing.

Commits

1. Failing test. LinqTests/Includes/include_on_the_queried_document_id.cs is a theory over query, lightweight, identity-map and dirty-tracked sessions, each with and without a duplicated field on the queried document. Before the fix, only query + duplicated failed.
2. The fix. Seven lines in TemporaryTableStatement.

Testing

Run locally on net10.0 against PostgreSQL:

• the new test: 8 of 8 pass;
• LinqTests: 1617 passed, 0 failed;
• CompiledQueryTests: 9 passed.

No public API changes.

[jeremydmiller]

Merged, thanks @Blackclaws — nice minimal fix, and the theory over all four session kinds made the A/B easy to verify (1/8 red on master, 8/8 green with the fix).

While reviewing I probed the adjacent shapes. Select() and Take() are fine, but a query session that also calls .Stats(out var stats) still fails with the same 42703 — and that one does not depend on a duplicated field, so it's a separate pre-existing hole rather than anything this PR missed. The StatsSelectClause wrapper means neither branch of the if fires. Filed as #5653 with the suggested fix.

If you want to pick that one up too, include_on_the_queried_document_id is the natural place for the coverage.