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/r84_const_reassign/case.ww

@@ -0,0 +1,3 @@
+//ww:error "cannot assign to const"
+package main;
+fn main() i32 = { const x: i32 = 5; x = 6; return x; };