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/r774_accept_wrapper_variant/case.ww

@@ -0,0 +1,14 @@
+//ww:run-exit 41
+// Migrated from 774_tagged_widen_named_variant row accept_wrapper_variant.
+package main;
+type unsupported = !void;
+type underread = !i32;
+type nomem = !void;
+type wrapper = !(unsupported | underread | nomem);
+type eof = void;
+fn f() (size | eof | wrapper) = {
+    let u: unsupported;
+    let e: wrapper = u;
+    return e;
+};
+export fn main() i32 = { let r = f(); return 41; };