Open work item modal when clicking on task in linked issues widget

What does this MR do and why?

This MR updates the issue detail page so that when you click on a task in the linked issues widget, a modal opens that shows the task's details.

• Before, a modal would only be opened when clicking on a task link in the description. However, we also want a modal to be opened when clicking on a task link in the linked issues widget
• After, a modal opens when clicking on a task link in the linked issues widget

I also got carried away and refactored a couple of specs that I touched, however note that I didn't fix everything and left some tech debt in there as it would require even more time that's outside the scope of this MR to complete.

No changelog required as it is behind the feature flag work_items, defaulted off.

• This is the first MR to resolve #365899 (closed). Ideally, every link to a task on the issues detail page should open in a modal
• The next MRs will open the work item modal when clicking on tasks in the description, comments, and system notes

Screenshots or screen recordings

Screen_Recording_2022-07-26_at_9.55.18_pm

How to set up and validate locally

1. In rails console enable the feature flag

   Feature.enable(:work_items)

2. Edit an issue's description to create some tasks, then save
3. Hover over a task, then click on the Create task + icon
4. Add the task to the Linked items widget
5. Click on the task in the description and the task in the linked issues widget to confirm they open in a modal

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.

Related to #365899 (closed)