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/r826_alias_tuple_ret/case.ww

@@ -0,0 +1,11 @@
+//ww:run-exit 7
+// Migrated from 826_alias_tuple_coerce row ret.
+package main;
+type pair = (int, int);
+fn f() pair = {
+	return (3, 4);
+};
+export fn main() i32 = {
+	let r: pair = f();
+	return (r.0 + r.1): i32;
+};