[pulsar-spark] upgrade SparkStreamingPulsarReceiver.java use pulsar-client and add spark example (#4143)

### Motivation

upgrade SparkStreamingPulsarReceiver.java use pulsar-client and add spark example

### Modifications

1. upgrade  SparkStreamingPulsarReceiver.java use pulsar-client, remove pulsar-client-1x pom
2. add  simple spark example
2 files changed