Thin 3.0: Unified exception handling

Java thin client uses the same public API interfaces as the server side.
Those user-facing APIs should behave in the same way on the server and client sides, including exceptions that may be thrown.

1. Remove IgniteClientException.
2. Keep IgniteClientConnectionException and other client-specific types. Inherit them from IgniteException.
3. When sending exception details from server to client, include the following:
   1. Code (group + error, see IgniteException.code)
   2. TraceId
   3. Message
   4. Fully-qualified class name
   5. OPTIONALLY: stack trace (Sensitive info. Send only when enabled in server-side ClientConnectorConfig. Disabled by default.)