Implement VerifySignedData() for ECDSA, RSA PKCS#1 and RSA PSS.

net/data/verify_signed_data_unittest/ecdsa-prime256v1-sha512-spki-params-null.pem

+This is the same test as ecdsa-prime256v1-sha512.pem except the public key's
+algorithm has been tampered with. The parameters for ecPublicKey should be a
+namedCurve, but here they have been replaced by NULL.
+
+
+
+-----BEGIN PUBLIC KEY-----
+MFEwCwYHKoZIzj0CAQUAA0IABJywz2kwPa/HYdTkaHtOzwOebTSrlkr4CBDY1VikqNb3LVEjOhe
+IkgqG7gihlix576MX+3h54pfa0hRtuZX6HHg=
+-----END PUBLIC KEY-----
+
+$ openssl asn1parse -i < [PUBLIC KEY]
+    0:d=0  hl=2 l=  81 cons: SEQUENCE          
+    2:d=1  hl=2 l=  11 cons:  SEQUENCE          
+    4:d=2  hl=2 l=   7 prim:   OBJECT            :id-ecPublicKey
+   13:d=2  hl=2 l=   0 prim:   NULL              
+   15:d=1  hl=2 l=  66 prim:  BIT STRING        
+
+
+
+-----BEGIN ALGORITHM-----
+MAoGCCqGSM49BAME
+-----END ALGORITHM-----
+
+$ openssl asn1parse -i < [ALGORITHM]
+    0:d=0  hl=2 l=  10 cons: SEQUENCE          
+    2:d=1  hl=2 l=   8 prim:  OBJECT            :ecdsa-with-SHA512
+
+
+
+-----BEGIN DATA-----
+bikyFTMBpO72gOZCiSmtrpiMEI1mijH/VdBImUfXX/gaRr+J6E1kAfAjvm6HaI+814TXhcqEZzV
+SSstS0ARSyEBApHnnzDMJNkQdk7vnIqlDKm4dsRK1yUA7ECcssTR/1hnUY/ep0iOtdv3gbYpog1
+APuEMjWr/5jiQb37VTjD4=
+-----END DATA-----
+
+
+
+-----BEGIN SIGNATURE-----
+A0cAMEQCIEufkeQoUocmGh0ckjz2Gc1SwXXP5/G+YKUljGEDSLo9AiAoxF+QHXHEGymGOOwNaoX
+X/LDDO7/sWpyBCEa2OSiahA==
+-----END SIGNATURE-----
+
+$ openssl asn1parse -i < [SIGNATURE]
+    0:d=0  hl=2 l=  71 prim: BIT STRING