[BUG]: add missing tests to `dstructs/named-typed-tuple`

[kgryte]

Currently, the implementation of dstructs/named-typed-tuple is missing tests.

We should add tests similar to how we have for, e.g., array/bool and array/complex128. Namely, test each prototype method individually.

Time estimate without AI: 16hrs
Time estimate with AI: 8-12hrs

[kgryte]

Let's deprioritize this one for the time being.