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/r989_cata_massign_alias/case.ww

@@ -0,0 +1,5 @@
+//ww:error "multi-assign rhs is not a tuple"
+package main;
+type pair = (i64, str);
+fn f() pair = { return (7i64, "hey"); };
+export fn main() i32 = { let a: i64 = 0i64; let s: str = ""; a, s = f(); return 0; };