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/r953_f64crossmod_x98_nested_arg/case.ww

@@ -0,0 +1,7 @@
+//ww:run-exit 242
+package myf;
+export fn g() f64 = { return -7.0; };
+package main;
+import myf;
+fn dbl(x: f64) f64 = { return x * 2.0; };
+export fn main() i32 = { return dbl(myf.g()): i32; };