Add lastupdated timestamp of progress to heirachy tree

What does this MR do and why?

Add last updated timestamp of progress to child hierachy tree

In the Child Objectives and KeyResults tree, add last updated time stamp of progress

Issue: #398560 (closed)

Screenshots or screen recordings

Screenshots are required for UI changes, and strongly recommended for all other merge requests.

How to set up and validate locally

1. Enable the okrs_mvc feature flag locally, and ensure you have an ultimate license
2. Go to any project and go to issues. Click the down arrow next to New Issue and change to New Objective, then click New Objective
3. Create a few sample objective to test with, they can be anything
4. Click into one of the created objectives and click Add next to Child objectives and key results, then click on Existing objective.
5. Hover on progress of the child items to see the tooltip.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.