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/r809idx_small_elem/case.ww

@@ -0,0 +1,4 @@
+//ww:run-exit 52
+package main;
+type one = struct { v: u64 };
+export fn main() i32 = { let a: [2]one; a[0].v = 2u64; a[1] = one { v = 5u64 }; return (a[1].v * 10u64 + a[0].v): i32; };