Remove the dependency on SecurityManager in JceSecurityManager.java

JceSecurityManager is a subclass of SecurityManager in order to get the class context and eventually the classes to determine if any required signing of providers or crypto permissions overriding of applications is necessary.

JEP 411 proposes to deprecate the SecurityManager for removal. If JEP 411 is approved, we will need to eventually remove the dependency "extends SecurityManager".

The class stack hierarchy can be obtained using the newer JDK 9 API StackWalker. Once the class is obtained, the CodeBase/ProtectionDomain jar verifications can proceed as before.