SSLEngine fixes for session cache, getError(), and unwrap() HandshakeStatus

[cconlon]

This PR includes the following fixes to SSLEngine:

• Only save the client session (WOLFSSL_SESSION) to the cache if the handshake has finished successfully and there is no outstanding error from wolfSSL_get_error() / getError(). This may prevent subsequent session resumption attempts trying to load/use a session that was in an error state.
• Synchronize calls to wolfSSL_get_error() / getError() with ioLock in case WOLFSSL state is changing. We want to prevent getting an error until activity is done/paused on the session.

This PR also fixes some issues found while testing wolfJSSE against the SunJSSE SSLEngine tests, including:

• Correctly return SSL_SUCCESS from WolfSSLEngine.ClosingConnection() when ZERO_RETURN is received
• Correctly return HandshakeStatus.FINISHED from SSLEngine.unwrap() when a client has received a TLS 1.3 session ticket from the peer. This necessitated also wrapping the native wolfSSL API wolfSSL_SESSION_has_ticket().

ZD 17962