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/r800append_struct_lit_two/case.ww

@@ -0,0 +1,9 @@
+//ww:run-exit 7
+package main;
+type pt = struct { x: i32, y: i32, z: i64 };
+export fn main() i32 = {
+	let xs: []pt = [];
+	append(xs, pt { x = 1, y = 2, z = 5 });
+	append(xs, pt { x = 3, y = 4, z = 7 });
+	return (xs[0].z + xs[1].z): i32 - xs[0].x - xs[1].y;
+};