Prevent Kafka Connect from leaking passwords and sensitive data

[orpiske]

We need to mark password and other sensitive fields with ConfigDef.Type.PASSWORD instead of ConfigDef.Type.STRING as we currently do (for example, here).

By annotating the fields as String, sensitive information is displayed on the logs:

camel.component.aws2-s3.accessKey = accesskey
...
camel.component.aws2-s3.secretKey

These values are likely leaking in other ways as well (to-be-confirmed: REST interface?)

After marking the field as password, this is what appears in the logs

camel.component.aws2-s3.secretKey = [hidden]

Although we have redacted them from our own logs, they still appear in logs printed by Kafka Connect itself (as reported on the - now - relevant related issue #320).

Since that issue has been closed for a while and since other sources of leakages have been fixed on #159, I opened this one with a specific goal in mind: prevent leakages on logs printed by Kafka Connect itself.

[orpiske]

Fixed.