* add `isNamedTuple`; make $(1, 2) be (1, 2) instead of leaking implementation detail (Field0: 1, Field1: 2)
fixes this: #8670 (comment) /cc @alehander42 @Vindaar @mratsim
* Note: isNamedTuple is useful in other places, eg #10010 (comment)
* move isNamedTuple to helpers.nim to avoid exposing new symbol to system.nim
* remove workaround in tests/vm/tissues.nim failing test now that #10218 was makes it work
