Move the crypto tests into the pkg directory

pkg/crypto/test/hmac_md5_test.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 // Library tag to allow the test to run on Dartium.
 library hmac_md5_test;
 
 import "package:expect/expect.dart";
 import "package:crypto/crypto.dart";
 
@@ skipping 95 matching lines @@
     Expect.isTrue(h.verify(macs[i]));
     Expect.isFalse(h.verify(macs[(i+1)%macs.length]));
     Expect.throws(() => h.verify([]));
   }
 }
 
 void main() {
   testStandardVectors(hmac_md5_inputs, hmac_md5_keys,
                       hmac_md5_string_macs, hmac_md5_macs);
 }