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/r830_cast_base_u32/case.ww

@@ -0,0 +1,8 @@
+//ww:run-exit 30
+// Migrated from 830_cast_base_index row u32_idx.
+package main;
+export fn main() i32 = {
+	let a: [4]u32 = [10u32, 20u32, 30u32, 40u32];
+	let i: int = 2;
+	return ((&a): *[4]u32)[i]: i32;
+};