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_andor_precedence/case.ww

@@ -0,0 +1,9 @@
+//ww:run-exit 42
+// Migrated from 700_e2e row 137.
+package main;
+type point = struct { x: i32, y: i32 };
+fn main() i32 = {
+  let p: *point = nil;
+  if (p != nil && p.x > 0 || p == nil) { return 42; };
+  return 1;
+};