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/r650_ptr_single_write/case.ww

@@ -0,0 +1,5 @@
+//ww:run-exit 42
+package main;
+type outer = struct { f: i32, g: i32 };
+fn set(o: *outer) void = { o.f = 42; };
+fn main() i32 = { let x: outer; x.f = 0; x.g = 0; set(&x); return x.f; };