[AMBARI-22886] Infra Manager: store s3 credentials in Hadoop credential store (#261)

* AMBARI-22886 Infra Manager: store s3 credentials in Hadoop credential store

* AMBARI-22886 Infra Manager: store s3 credentials in Hadoop credential store
- addendum: use Optional<String> as a return type of getPassword, remove unnecessary ArrayList
16 files changed