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/r650_value_2deep_read_write/case.ww

@@ -0,0 +1,5 @@
+//ww:run-exit 15
+package main;
+type inner = struct { a: i32, b: i32, c: i32 };
+type outer = struct { i: inner, x: i32 };
+fn main() i32 = { let o: outer; o.i.a = 10; o.x = 5; return o.i.a + o.x; };