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_nested_index_arg/case.ww

@@ -0,0 +1,20 @@
+//ww:run
+package main;
+fn dup1(s: str) str = { return s; };
+fn streq(a: str, b: str) bool = {
+	if (a.len != b.len) { return false; };
+	let i: i32 = 0;
+	for (i < a.len) {
+		if (a[i] != b[i]) { return false; };
+		i += 1;
+	};
+	return true;
+};
+fn main() i32 = {
+	let argv: [3]str;
+	argv[0] = "a";
+	argv[1] = "bb";
+	argv[2] = "files.txt";
+	if (!streq(dup1(argv[2]), "files.txt")) { return 11; };
+	return 0;
+};