Issue Summary

If a user tries to add either "Days remaining in sprint" or "Sprint health" to their Dashboard, there is no way to Search for an existing Board. (Note: both Search and ABC sorting are available for Projects). 

Searching for an appropriate Board is very time-consuming in larger orgs, or orgs with multiple Boards. Scrolling takes time, and Cmd+F does not work (it closes the widget Configuration).

Because these options are not available, our Customers are impacted (per the Company values).

Additionally, the Sprint Health Gadget is heavily promoted in Atlassian blogs, i.e. here: https://www.atlassian.com/blog/jira-software/7-steps-to-a-beautiful-and-useful-agile-dashboard 

Steps to Reproduce

1. Go to Dashboards --> add a widget --> Days remaining in sprint
2. Look for your Board, or click "Configure" to modify already-existing gadget
3. Board search or ABC sorting is not available, so you have to scroll through the entire list
4. Repeat the same for the Sprint health gadget to validate

Expected Results 

User should be able to search Boards in all widgets, or at least see the existing boards sorted alphabetically. The ABC sorting is MVP.

Actual Results

There is no Search or ABC sorting available for Boards.

Workaround

User has to scroll through the entire list of Boards.