Port config hot-reload (44 tests), opts (1 test), account isolation
(5 tests), auth callout (5 tests), and JWT validation (11 tests) from
Go reload_test.go, opts_test.go, accounts_test.go, auth_callout_test.go,
and jwt_test.go as behavioral blackbox integration tests against the
.NET NatsServer using ReloadOptions() and the public NATS client API.
