Pull Request Diff tab : Focus indicator is not visible for the file path link

Issue Summary

In the diff page for pull requests, the file path link for the currently opened file has no focus indicator visible.

Steps to Reproduce

1. Launch the URL
2. In the Diff section of the pull request, Navigate to the commit path section under the Filter file tree and Search code button.
3. Navigate with the keyboard on the path of the file available.

Screenshot

Screen Recording

Screen Recording 2022-05-03 at 1.32.47 PM.mov

Actual Results

When users navigate to the file link in the diff section for pull requests in the main content area of the page, it is not possible to visually identify the current location on the “file” link. No focus indicator is visually available as the user tabs through the links using a keyboard.

Expected Results

Provide a clear visual indication to users when their focus moves from one interactive web page element to another. This will help all users while accessing the page content, especially users with visual, mobility and learning impairments.  
Common keyboard focus indicator solutions include:

• A 2px box around the focused element
• A change in the background colour of the focused element
• The addition of an icon, such as an arrow, next to a menu item
• The addition of a thick line under or next to the focused element
• A distinctive change to the text of the component such as making it bold and/or underlined
• Use the default browser focus indicator. NOTE: Since each browser has its own default focus indicator style, check each of the major browsers (Chrome, Firefox, Edge, IE, Safari) to ensure the default focus indicator is visible as you tab through the page. 

Workaround

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

Bug Ref:737350