Don't fill context.session if the session is invalid

[dcousens]

Previously, the auth.*.test.ts tests checked authentication by enforcing that context.session.data exists, not by checking that context.session exists.
This thinking was somewhat proliferated throughout the examples by sometimes checking things like context.session?.data?.isAdmin, but, not necessarily consistently.
Many examples (see auth/schema.ts, examples-staging/ecommerce) actually use context.session?.data.isAdmin, which, previous to this change, could break.

I think the presence of a .session object itself is what indicates the session is valid, as provided by the session strategy.
The .session.data should additionally be guaranteed to exist, not optional depending on whether the user still exists.

This pull request enforces that the .data query succeeds and returns data, as a precondition to whether a .session is valid and provided.

[changeset-bot]

🦋 Changeset detected

Latest commit: b2a2d76

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@keystone-next/auth	Patch

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[emmatown]

Needs a changeset