Better error message for not invoking AccountUpdate.requireSignature()

[rpanic]

Currently, if you forget to invoke requireSignature() on a AccountUpdate but try to test it on localBlockchain with proofs turned off, you get

Assert_failure src/lib/transaction_logic/zkapp_command_logic.ml:1266:17
      at raise_error (../../../../home/gregor/.opam/4.14.0/lib/js_of_ocaml-compiler/runtime/jsoo_runtime.ml:110:3)
      at apply_json_transaction (../../../../workspace_root/src/lib/snarky_js_bindings/lib/snarky_js_bindings_lib.ml:2933:11)
      at caml_call_gen (../../../../builtin/+stdlib.js:32:12)
      at Object.applyJsonTransaction (../../../../builtin/+jslib.js:289:12)
      at Object.sendTransaction (node_modules/snarkyjs/src/lib/mina.ts:436:16)
      at sendTransaction (node_modules/snarkyjs/src/lib/mina.ts:1021:10)
      at Object.send (node_modules/snarkyjs/src/lib/mina.ts:299:14)
      at Object.<anonymous> (src/lending/Lender.test.ts:427:20)

This error can lead to a lot of confusion and can be easily replaced by checking that in sendTransaction in the localBlockchain implementation

[mitschabaude]

duplicate of #808