test/wcc/data: grow the declarative compiler corpus to 1,224 fixtures

The r-prefixed waves absorb the runtime, reject, and byte-compare rows
of the migrated native carriers; each fixture is one directory with one
case.ww and a //ww:error, //ww:compile, //ww:run, or //ww:run-exit
directive covering both frontends.

test/wcc/data/r680_val_arr_str_field/case.ww

@@ -0,0 +1,10 @@
+//ww:run-exit 5
+package main;
+type nd = struct { name: str, x: i32 };
+fn setit(p: *nd, s: str, vv: i32) void = { p.name = s; p.x = vv; };
+fn main() i32 = {
+	let arr: [4]nd;
+	setit(&arr[1], "world", 100);
+	let s: str = arr[1].name;
+	return s.len: i32;
+};