fix(parser): Correctly handle ? postfixed element type in TupleType

[leaysgur]

For example:

declare let tx4: [(string | undefined)?]

The current logic relied on the span position to determine whether ? should mean JSDocNullableType or OptionalType.

Therefore, the parsing results seemed to change depending on whether the preserveParens option was enabled or not.

[graphite-app]

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[codspeed-hq]

CodSpeed Instrumentation Performance Report

Merging #10390 will not alter performance

_{Comparing fix/optional-tuple-type (7e0b370) with main (41d8e9d)}

Summary

✅ 36 untouched benchmarks