Simplify KeyChain API by removing now unneeded CA certificate lookup (1 of 3)

frameworks/base

   Remove getCaCertificates and findIssuer from IKeyChainService,
   these are now done via libcore's TrustedCertificateStore (as part
   of the default TrustManager implementation)

	keystore/java/android/security/IKeyChainService.aidl

   Simplify KeyChain API. Now that the CA certificates are visible
   through the default TrustManager, the KeyChain is solely focused on
   retrieving PrivateKeys and their associated certificates. The
   calling API for KeyChain to simply a single KeyChain.get() call
   that returns a KeyChainResult, removing the need for a KeyChain
   instance that needs to be closed.

	keystore/java/android/security/KeyChain.java
	keystore/java/android/security/KeyChainResult.java

master/libcore

    Remove getDefaultIndexedPKIXParameters and
    getIndexedPKIXParameters which was used as part of the prototype
    of looking up CAs via the KeyChain but is obsoleted by the new
    default TrustManager implementation.

	luni/src/main/java/org/apache/harmony/xnet/provider/jsse/SSLParametersImpl.java
	luni/src/main/java/org/apache/harmony/xnet/provider/jsse/TrustManagerImpl.java

packages/apps/KeyChain

    Tracking simplified IKeyChainService, removing now unneeded
    implementation, updating tests.

	src/com/android/keychain/KeyChainService.java
	tests/src/com/android/keychain/tests/KeyChainServiceTest.java
	tests/src/com/android/keychain/tests/KeyChainTestActivity.java

Change-Id: I847b28c2f467c85f24d2b693a2fecc1cb46426b4