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_accessors_string_buffer_reset/case.ww

@@ -0,0 +1,22 @@
+//ww:run-exit 46
+// Migrated from 776_memio_vstream_run row accessors_string_buffer_reset.
+package main;
+import memio;
+import io;
+import os;
+export fn main() i32 = {
+    let buf: [16]u8;
+    let st: memio.stream = memio.fixed(buf[0:16]);
+    let s: io.stream = &st.vt;
+    let payload: [3]u8;
+    payload[0] = 65u8; payload[1] = 66u8; payload[2] = 67u8;
+    let wr = io.write(s, payload[0:3]);
+    if (!(wr is size)) { return 90; };
+    let v: str = memio.string(&st);
+    if (v.len != 3 || v[0] != 65u8 || v[2] != 67u8) { return 91; };
+    let bv: []u8 = memio.buffer(&st);
+    if (bv.len != 3 || bv[1] != 66u8) { return 92; };
+    memio.reset(&st);
+    if (memio.string(&st).len != 0) { return 93; };
+    return 46;
+};