HHH-19085 NPE when using null value in CriteriaUpdate

[ThomasReinhardt]

Fix for HHH-19085

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[mbladel]

@ThomasReinhardt thanks for trying to fix this issue! Your solution only accounts when using INLINE value handling by defaulting to a null literal whenever we have a null value. We should rather fix the source of the problem, by correctly supporting null values in the SqmCriteriaNodeBuilder methods called by value, i.e. both literal and valueParameter.

From the stack trace in your Jira issue, the problem seems to be in EntityType#isInstance, though the line-numbers don't align with current main code.

As an additional note, we require that bugfix PRs include test cases that highlight the problem you're trying to fix and ensure no regression is introduce at a later point, so please add one here.