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/r806_tryprop_reject_try_is/case.ww

@@ -0,0 +1,11 @@
+//ww:error c "is on non-tagged-union" ww "is/as: operand is not a tagged union"
+package main;
+
+fn f(k: i32) (i32 | nomem) = { return 7; };
+
+fn g() (i32 | nomem) = {
+	if (f(1)? is i32) { return 1; };
+	return 0;
+};
+
+export fn main() i32 = { return 0; };