System dashboard: Table sort functionality is inaccessible

Steps to reproduce:

1. Navigate to the "Assign to me" data table present in the main region of page.
2. Using Tab key try to navigate to the "P" column’s sort by priority interactive element.

Screen recording:

144.mov

Actual behaviour:

Keyboard users are unable to use the sort functionality as the sort interactive element fails to receive Tab focus. In addition, when screen reader users try to navigate to the sort element, it does not announce correct role of button to them. Thus they might have difficulties in accessing the sort functionality.

Expected result:

Expected result:
The sort functionality should be accessible for keyboard only as well as screen reader users.

1. The "P" sort button should receive a tab stop when users try to navigate through the table using Tab key.
2. When the sortable table headers such as "P" receive keyboard focus, they should be announced as buttons to screen reader users.
3. When screen reader users navigate through the table columns in "Read" mode, the current sort order should be announced to them.
4. On activating the sort button, the value of "aria-sort" should be updated programmatically with the focus staying on the sort button itself.

For more information on implementation, please refer 2nd example in link- https://w3c.github.io/aria-practices/examples/grid/dataGrids.html

AXQA Ref:AXQA-143