Add key binding to open subreddit of currently selected thread

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Is your feature request related to a problem? Please describe.
When browsing a page where threads of many different subreddits are listed (like /r/front, r/all), it would be nice to have a keybinding to open the subreddit of the currently selected thread.

Describe the solution you'd like
Simply define a key which opens the subreddit instead of needing to use the prompt and manually typing the subreddit name.

Describe alternatives you've considered
The currently available alternative is to manually type the subreddit name in the prompt. But this should be simplified.