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/r775_closer_set/case.ww

@@ -0,0 +1,15 @@
+//ww:run-exit 60
+// Migrated from 775_io_vtable_run row closer_set.
+package main;
+import io;
+fn myclose(s: io.stream) (void | io.error) = {
+    return void;
+};
+export fn main() i32 = {
+    let vt: io.vtable;
+    vt.closer = (&myclose): *io.closer;
+    let v: io.stream = &vt;
+    let r = io.close(v);
+    if (r is void) { return 60; };
+    return 99;
+};