SAMZA-2561: Add job features to MetricsHeader

[PawasChhokra]

Issues: Currently, the MetricsHeader object emitted by the SamzaContainer does not exclude basic job level information. Changes: Added a few features of the job to be emitted by the MetricsHeader API Changes: With this change, the MetricsHeader class will emit other properties of the job like number of containers used, number of cores used, etc. Upgrade instructions: None Usage instructions: None Tests: Modified existing tests to work with this change.

[rmatharu-zz]

Since a majority of the parameters are derived from config, in the interest of easy future extensibility, it'd be better to simply emit the entire config object once, from DiagnosticsManager at container-startup. Similar for dependencies.