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/r76_infer_struct_ident_chain/case.ww

@@ -0,0 +1,6 @@
+//ww:run-exit 33
+package main;
+type point = struct { a: i64, b: i64 };
+fn make(flag: i32) point = { if (flag == 0) { return point { a = 11i64, b = 22i64 }; }; return point { a = 110i64, b = 220i64 }; };
+fn sum(p: point, which: i32) i32 = { if (which == 0) { return (p.a + p.b): i32; }; return (p.a - p.b): i32; };
+fn main() i32 = { let q = make(0); let p = q; return sum(p, 0); };