Backlog: drag and drop is not accessible for screen reader & keyboard-only users.

Issue Summary

On the Backlog page, the drag and drop functionality for the Issues is not accessible for screen reader & keyboard users.

Steps to Reproduce

1. Navigate to the backlog page.
2. Navigate to the Issues to drag & drop.

Actual Results

There are multiple issues with the current implementation of the drag & drop functionality on the backlog page.

1. The buttons have incomplete labels. Only the instructions are announced by the screen reader. 
2. The keyboard behaviour is different as compared to the "Kanban board" page. 
3. The user can’t move issue from "backlog" to "sprint" section with keyboard-alone.
4. There are few bugs when using keyboard. when an issue in sprint section is focused & when user try to move within sprint then a modal shows "Issue will be moved from Sprint to backlog". And same thing happens when user tries to move issue within backlog section

Screen recording

https://www.loom.com/share/23132a0efe5b4b64806070be1f36443b?sid=306e67f4-bcfb-442c-a330-9e5cac10e091 

Expected Results

1. The Button should have complete & descriptive labels as provided on the kanban board page.
2. The keyboard behaviour should be same as the one on "Kanban board page". 
3. The user should be able to move issue from "backlog" to "sprint" section with keyboard-alone.
4. There shouldn’t be any bugs when dragging & dropping issue with keyboard alone.

Workaround

Currently there is no known workaround for this behavior. A workaround will be added here when available