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_alloc_shadow_myos/case.ww

@@ -0,0 +1,10 @@
+//ww:run-exit 107
+// Migrated from 700_e2e row 40.
+package myos;
+fn alloc(n: i64) i64 = { return n + 100; };
+fn run() i64 = { return alloc(7); };
+package main;
+import myos;
+fn main() i32 = {
+  return myos.run(): i32;
+};