Ensure RSS icon is present on all repo tabs (#23904)

Ensure RSS icon is present on all repo tabs (#23904)

Previously, not all repo tabs had shown the RSS icon in the repo header
because the context data was not being set. Added this context data in a
new function.

Before:

<img width="806" alt="image"
src="https://user-images.githubusercontent.com/115237/229639615-9cc00e75-3a26-4ff4-a6f2-316c1fccc596.png">

After:

<img width="815" alt="Screenshot 2023-04-04 at 00 16 17"
src="https://user-images.githubusercontent.com/115237/229639201-2e1c015b-1f13-46d4-aa14-e7a82fab3982.png">

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Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>