SEP-45: Handle require_auth in __check_auth

[philipliu]

A recording simulation will not generate authorization entries required by a client contract's __check_auth implementation if it has nested require_auths. However, the client must provide these entries in the token request for the enforcing simulation to succeed. These entries do not follow the same format as the auth entries generated by the recording simulation and cannot not be verified by the server when receiving a token request.

An example of such auth entry looks like:

{
  "credentials": {
    "address": {
      "address": "GB36W6FIDEPLAH2XNM3CKJR4QRCKWVIKQANKOGWJN6NC6J3X5SVMUCPR",
      "nonce": 5990244105667177314,
      "signature_expiration_ledger": 1070813,
      "signature": {
        "vec": [
          {
            "map": [
              {
                "key": {
                  "symbol": "public_key"
                },
                "val": {
                  "bytes": "77eb78a8191eb01f576b3625263c8444ab550a801aa71ac96f9a2f2777ecaaca"
                }
              },
              {
                "key": {
                  "symbol": "signature"
                },
                "val": {
                  "bytes": "5a4147e292b3019fceb86833948642865bdb12ec71e0cf24f3238090461f6f73c2896a132b089a3c642b0b46f1500fa28cffdc4831a73e4cde52e557b9ba9c06"
                }
              }
            ]
          }
        ]
      }
    }
  },
  "root_invocation": {
    "function": {
      "contract_fn": {
        "contract_address": "CAASCQKVVBSLREPEUGPOTQZ4BC2NDBY2MW7B2LGIGFUPIY4Z3XUZRVTX",
        "function_name": "__check_auth",
        "args": [
          {
            "bytes": "ad31a086eeb53572dd5ac8c06f272c3dd86eb556ee765b9ad1c75b7691c1e6e6"
          }
        ]
      }
    },
    "sub_invocations": []
  }
}

GB36W6FIDEPLAH2XNM3CKJR4QRCKWVIKQANKOGWJN6NC6J3X5SVMUCPR auth is required for a client contract CAASCQKVVBSLREPEUGPOTQZ4BC2NDBY2MW7B2LGIGFUPIY4Z3XUZRVTX's __check_auth.

This PR relaxes the authorization entry verification performed by the server so that arbitrary authorization entries can be included in the token request.