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/r79_xmod_valglobal_f64/case.ww

@@ -0,0 +1,8 @@
+//ww:run-exit 2
+package aa;
+export let f: f64 = 2.5;
+export fn getf() f64 = { return f; };
+package main;
+import aa;
+let f: f64 = 9.9;
+export fn main() i32 = { return aa.getf(): i32; };