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/r776_fixed_read_5/case.ww

@@ -0,0 +1,19 @@
+//ww:run-exit 42
+// Migrated from 776_memio_vstream_run row fixed_read_5.
+package main;
+import memio;
+import io;
+import os;
+export fn main() i32 = {
+    let buf: [8]u8;
+    buf[0] = 65u8; buf[1] = 66u8; buf[2] = 67u8; buf[3] = 68u8;
+    buf[4] = 69u8; buf[5] = 70u8; buf[6] = 71u8; buf[7] = 72u8;
+    let st: memio.stream = memio.fixed(buf[0:8]);
+    let s: io.stream = &st.vt;
+    let out: [5]u8;
+    let n: size = 0;
+    let rd = io.read(s, out[0:5]);
+    if (rd is size) { n = rd as size; };
+    if (n == 5: size && out[0] == 65u8 && out[4] == 69u8) { return 42; };
+    return 99;
+};