[GOBBLIN-2244] Populate file set property in CopyableFile for IcebergFileStreamExtractor

[thisisArjit]

…ctor

Dear Gobblin maintainers,

Please accept this PR. I understand that it will not be reviewed until I have checked off all the steps below!

JIRA

• My PR addresses the following Gobblin JIRA issues and references them in the PR title.
  • https://issues.apache.org/jira/browse/GOBBLIN-2244

Description

• Populate file set property in CopyableFile for IcebergFileStreamExtractor
• This is required to ensure correct grouping of work units & sequence of publish step

Tests

• Minor change, tested locally that pre-publish step is in correct order & called only once

Commits

• My commits all reference JIRA issues in their subject lines, and I have squashed multiple commits if they address the same issue. In addition, my commits follow the guidelines from "How to write a good git commit message":
  1. Subject is separated from body by a blank line
  2. Subject is limited to 50 characters
  3. Subject does not end with a period
  4. Subject uses the imperative mood ("add", not "adding")
  5. Body wraps at 72 characters
  6. Body explains "what" and "why", not "how"