Remove deprecated java.security.{Certificate,Identity,IdentityScope,Signer} APIs

Summary

Remove the following terminally deprecated APIs that have been marked for removal since Java SE 10: java.security.Certificate, java.security.Identity, java.security.IdentityScope, and java.security.Signer.

Problem

In Java SE 10, these APIs were marked for removal (see JDK-8175091). These APIs have been deprecated since Java SE 1.2. They have been superseded by other APIs and no longer have any value.

Solution

1. Remove the java.security.Certificate, java.security.Identity, java.security.IdentityScope, and java.security.Signer classes.
2. Remove the following java.security.SecurityPermission targets that are related to these APIs and no longer would have any value: setSystemScope, setIdentityPublicKey, setIdentityInfo, addIdentityCertificate, removeIdentityCertificate, printIdentity, getSignerPrivateKey, and setSignerKeyPair.
3. Remove the policy.ignoreIdentityScope security property which is specific to the IdentityScope API.

Specification

See attached webrev.zip.