WI Bug: add child and remove child quick action doesn't update hierarchy widget until page refresh

What does this MR do and why?

This MR updates the getWorkItemTreeQuery apollo query cache, for the Add, Create and Remove Child actions. So we can correctly update the Child Items count without the need of a page refresh.

References

This MR got inspiration from the following MR !171817 (merged) which was mentioned in the following discussion: #498118 (comment 2534602290)

Screenshots or screen recordings

Before	After
BEFORE.mp4	AFTER.mp4

How to set up and validate locally

Go to an issue, in a Repo and try to add and remove Child Items. It should automatically update the Child Items count with out the need to reload the page

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