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_global_structlit/case.ww

@@ -0,0 +1,5 @@
+//ww:run-exit 18
+package main;
+type pt = struct { x: size, y: size, z: size };
+let g: pt = pt { x = 0: size, y = 0: size, z = 0: size };
+export fn main() i32 = { g = pt { x = 5: size, y = 6: size, z = 7: size }; return (g.x + g.y + g.z): i32; };