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_spread_variant_match_compile/case.ww

@@ -0,0 +1,6 @@
+//ww:compile
+package main;
+type inner = (i64 | bool | rune);
+type field = (...inner | str);
+fn classify(f: field) i64 = { match (f) { case let n: i64 => return n; case let b: bool => return 1; case let r: rune => return 2; case let s: str => return s.len: i64; }; };
+export fn main() i32 = { return 0; };