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/r815_int_printf/case.ww

@@ -0,0 +1,6 @@
+//ww:run-exit 54
+package main;
+import os;
+import fmt;
+import io;
+export fn main() i32 = { let buf: [16]u8; let x: int = 42; let v: str = ""; match (fmt.bsprintf(buf[0:16], "{}", x)) { case let s: str => { v = s; }; case io.error => { return 91; }; }; if (v.len != 2) { return 92; }; if (v[0] != 52u8 || v[1] != 50u8) { return 93; }; return 54; };