Expand when isNewIdentifierLocation is set in the syntax server

[DanielRosenwasser]

In #37713, we might not have a full picture of the world, so it might overly restrictive to only suggest identifiers in the current file. We should consider being more permissive so that editors don't aggressively auto-complete on identifiers in these contexts.

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Aside: if we do this, we should make sure that the work done in #38836 doesn't cause conflicts.

For example, let's say you have an empty file like

thing/**/

and completions get triggered at /**/. A user should not get completions for thing at that point.