signature: deprecate Signature in favor of SignatureInfo

The Signature in Data packets and Certificates
has been deprecated in favor of separate objects
representing the Signature info and value.

Also deprecate type-specific Signature helpers.

refs #4804

Change-Id: Iab5b5c618e75cc11d31801d86a89a550a6add7a0
diff --git a/tests/make-interest-data.cpp b/tests/make-interest-data.cpp
index 09d879b..c6e3a4c 100644
--- a/tests/make-interest-data.cpp
+++ b/tests/make-interest-data.cpp
@@ -46,9 +46,8 @@
 Data&
 signData(Data& data)
 {
-  ndn::SignatureSha256WithRsa fakeSignature;
-  fakeSignature.setValue(ndn::encoding::makeEmptyBlock(tlv::SignatureValue));
-  data.setSignature(fakeSignature);
+  data.setSignatureInfo(SignatureInfo(tlv::SignatureSha256WithRsa));
+  data.setSignatureValue(encoding::makeEmptyBlock(tlv::SignatureValue));
   data.wireEncode();
   return data;
 }