test: migrate 700_e2e rows to corpus fixtures; retire the carrier

136 rows migrated, 0 already owned, 3 wwstage-failing rows held out.

test/wcc/data/r700_fmt_println_size/case.ww

@@ -0,0 +1,11 @@
+//ww:run-exit 8
+// Migrated from 700_e2e row 132.
+package main;
+import fmt;
+import io;
+fn main() i32 = {
+  match (fmt.println("hello", 7i64)) {
+  case let n: size => return n: i32;
+  case let _e: io.error => return -1;
+  };
+};