cue/testdata: add regression test for https://cuelang.org/issue/3805

Fixes #3805.

Signed-off-by: Paul Jolly <[email protected]>
Change-Id: Iec029b234d0e63a7563bea0bba659affb85fc1c2
Reviewed-on: https://review.gerrithub.io/c/cue-lang/cue/+/1211873
Reviewed-by: Daniel Martí <[email protected]>
TryBot-Result: CUEcueckoo <[email protected]>
Unity-Result: CUE porcuepine <[email protected]>

Author: myitcv