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/r71_arrlit_index_len_arg/case.ww

@@ -0,0 +1,9 @@
+//ww:run-exit 5
+package main;
+fn ident(n: i32) i32 = { return n; };
+fn main() i32 = {
+	let xs: [2]str;
+	xs[0] = "hi";
+	xs[1] = "hello";
+	return ident(xs[1].len: i32);
+};