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/r921_amp_def_struct/case.ww

@@ -0,0 +1,6 @@
+//ww:run-exit 18
+package main;
+type pt = struct { x: i32, y: i32 };
+def P: pt = pt{x=7, y=11};
+fn rd(p: *pt) i32 = { return p.x + p.y; };
+export fn main() i32 = { return rd(&P); };