Fetch remote users if they are not found.

[TomCarroll09]

Pitch

If I were to search for a user and press the "go to user" quick action, mastodon will load the users page, but if the user isn't known to the server it will give an error. For example, I have an account for testing some stuff on mas.to (mas.to/ire) but if I open it on, for example, mastodon.social (mastodon.social/@[email protected]) it will give a 404 because the account is unknown. Contrast this to Sharkey, which will automatically fetch the user and display their page.

Motivation

While you can just paste the URL to the account in directly, it makes sense (in my opinion) to be able fetch an account through a handle as well. Another benefit would be for users who host a webfinger endpoint on their website which links to their mastodon handle, as that would have no url to fetch from.