Resolve "Need for a more flexible mechanism to provide the pulsar connection string"

Closes #92 (closed)

I needed to change my original approach a little bit and created the DEPulsarConnector class. It allows the usage as following:

const pulsarConnection = new DEPulsarConnector(host, port, topic).connect()

or

const pulsarConnection = new PulsarConnection(DEPulsarConnector.connectionParameter(host, port, topic))

I wanted to make the overall mechanism flexible (which it should with the 2 new interfaces) and easy to migrate (with both solutions shown here with the DEPulsarConnector should provide).

Let me know what you think about it.