Implement methods of ObjectUnderFileSystem

[pkuweblab]

What changes are proposed in this pull request?

Add method getObjectTags() and setObjectTagging() to UnderFileSystem class under alluxio-underfs

Why are the changes needed?

merge latest change of COSUnderFileSystem into master-2.x

Does this PR introduce any user facing changes?

[alluxio-bot]

Automated checks report:

• PR title follows the conventions: FAIL
  • The title of the PR does not pass all the checks. Please fix the following issues:
    • Title is too long (86 characters). Must be at most 72 characters.
• Commits associated with Github account: PASS

Some checks failed. Please fix the reported issues and reply 'alluxio-bot, check this please' to re-run checks.

[alluxio-bot]

Automated checks report:

• PR title follows the conventions: PASS
• Commits associated with Github account: PASS

All checks passed!

[pkuweblab]

@Jackson-Wang-7 ask for review