Adds GitHub-like pages to view watched repos and subscribed issues/PRs
This is my second try to fix this, but it is better than the first since
it doesn't uses a filter option which could be slow when accessing
`/issues` or `/pulls` and it shows both pulls and issues (the first try
is #17053).
Closes #16111
Replaces and closes #17053
Co-authored-by: Lauris BH <lauris@nix.lv>
Co-authored-by: 6543 <6543@obermui.de>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>
