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/r701_one_i64_let_call/case.ww

@@ -0,0 +1,8 @@
+//ww:run-exit 7
+package main;
+type one = struct { v: i64 };
+fn mk() one = { return one { v = 7i64 }; };
+fn main() i32 = {
+	let s: one = mk();
+	return s.v: i32;
+};