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_mixed/case.ww

@@ -0,0 +1,7 @@
+//ww:run-exit 57
+package main;
+import os;
+import fmt;
+import io;
+import memio;
+export fn main() i32 = { let buf: [32]u8; let st: memio.stream = memio.fixed(buf[0:32]); let vs: io.stream = &st.vt; let x: int = 1; match (fmt.fprint(vs, x, 2i64, true)) { case size => {}; case io.error => { return 91; }; }; let v: str = memio.string(&st); if (v.len != 8) { return 92; }; if (v[0] != 49u8 || v[1] != 32u8) { return 93; }; if (v[2] != 50u8 || v[3] != 32u8) { return 94; }; if (v[4] != 116u8 || v[7] != 101u8) { return 95; }; return 57; };