Pulsar Component - missing features

[crtomirmajer]

Pulsar component is missing some important features:

• support for Token/OAuth2 Authentication, currently none. I suggest adding the following:

pulsar:
    auth:
        oauth2:
          audience: "urn:sn:pulsar:x:y"
          issuer_url: "https://auth.xyz"
          private_key_file: /this/folder/key.json
        token:
          token: <base64-token-here> 

• configurable subscription type, currently hardcoded to Shared. My proposal is to add subscription_type option:

pulsar:
   subscription_type: <type-here>  # one of: shared, key_shared, exclusive, failover

• message attributes, such as id, publishTime, redeliveryCount, etc. (see Message interface)