ww: finish initialization validation parity

test/wcc/data/r687_neg_str_slicelit/case.ww

@@ -1,4 +1,4 @@
-//ww:error "slice-of-{str,slice,tagged} literal static-init unsupported"
+//ww:run-exit 2
 package main;
 let g: []str = ["a", "b"];
 export fn main() i32 = { return g.len: i32; };