Adds a method to `TStringValue` to detect whether the t-string is empty _as an iterable_. Note the subtlety here that, unlike f-strings, an empty t-string is still truthy (i.e. `bool(t"")==True`). Closes #19951
Adds a method to `TStringValue` to detect whether the t-string is empty _as an iterable_. Note the subtlety here that, unlike f-strings, an empty t-string is still truthy (i.e. `bool(t"")==True`). Closes #19951