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/r956_modqual_mq_f64_str_destr/case.ww

@@ -0,0 +1,15 @@
+//ww:run-exit 4
+package myf;
+export fn fs(n: f64) (f64, str) = {
+	if (n == 0.0) { return (n, "x"); };
+	return (n, "hello");
+};
+package main;
+import myf;
+export fn main() i32 = {
+	let (f, s) = myf.fs(4.0);
+	let g: f64 = f + 0.0;
+	if (g != 4.0) { return 1; };
+	if (s.len != 5) { return 2; };
+	return (f: i32);
+};