Add list/search community on sidebar

[Xanvial]

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** Describe the feature request below **

Currently on navigation bar there's a button to show a page containing list of subscribed community, with search bar that can search all community (including from other federated instances). But only the subscribed list that exist on sidebar. Which is why when Show Navigation Bar setting is disabled, there's no way to search other community.

I propose to duplicate the community button in navigation bar to sidebar, same as other buttons (like inbox, saved, and profile)