feat: Add time spent tracking to tuple write command

[Siddhant-K-code]

Description

This PR adds time tracking functionality to the tuple write command, displaying how long operations take to complete using Go's standard duration formatting.

Example output:

{
  "failed_count": 1,
  "successful_count": 1,
  "total_count": 2,
  "time_spent": "2.976ms"
}

References

fixes #448

Review Checklist

• I have clicked on "allow edits by maintainers".
• I have added documentation for new/changed functionality in this PR or in a PR to openfga.dev [Provide a link to any relevant PRs in the references section above]
• The correct base branch is being used, if not main
• I have added tests to validate that the change in functionality is working as expected

[Siddhant-K-code]

@ewanharris, it looks good to go now 🚀

---

Regarding Squashing commits, I think, we can do that while merging PR from GitHub UI by selecting Squash & Merge option

[ewanharris]

Thanks @Siddhant-K-code! 🚀