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/r812_assign_odd_12b/case.ww

@@ -0,0 +1,4 @@
+//ww:run
+package main;
+type tri = struct { a: u32, b: u32, c: u32 };
+export fn main() i32 = { let x: tri = tri { a = 7: u32, b = 8: u32, c = 9: u32 }; let y: tri = tri { a = 0: u32, b = 0: u32, c = 0: u32 }; y = x; if (y.a != 7) { return 1; }; if (y.b != 8) { return 2; }; if (y.c != 9) { return 3; }; return 0; };