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_argc/case.ww

@@ -0,0 +1,4 @@
+//ww:run-exit 1
+// Migrated from 700_e2e row 21.
+package main;
+fn main(argc: i32, argv: **u8) i32 = { return argc; };