Refactor sidebar health status widget to use SidebarEditableItem

What does this MR do and why?

This MR refactors the sidebar health status widget to use SidebarEditableItem, which the other sidebar widgets now use for reusing logic. This allows us to delete a bunch of duplicate code. Also:

• Renames "status" to "health status" to be less confusing, as "status" can also be confused for open/closed status
• Simplifies/removes/co-locates a bunch of code

Screenshots or screen recordings

issue sidebar	bulk edit issues sidebar
Screen_Recording_2022-10-11_at_5.21.18_pm	Screen_Recording_2022-10-11_at_5.27.27_pm

How to set up and validate locally

1. Go to an issue and test the health status widget in the right sidebar
2. Go to the issues list page, click Edit issues, and test the health status dropdown in the right sidebar

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.