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/r913_def_mangle_multi/case.ww

@@ -0,0 +1,7 @@
+//ww:run-exit 100
+// Source-level runtime half of 913_def_mangle_run.c multi_def.
+package main;
+def A: u64 = 10u64;
+def B: u64 = 30u64;
+export def C: u64 = 60u64;
+export fn main() i32 = { return (A + B + C): i32; };