up-line-or-beginning-search integration

[zoriya]

On zsh, atuin can almost fully replace the built-in history as it integrate with zsh-autosuggestion, ctrl-r and co.

I would like to keep my default Up binding of up-line-or-beginning-search (which will search on the history for a command that matches the current prompt). Only issue: atuin isn't used as the history source, so only commands run in the current shell can be searched by the up-line-or-beginning-search widget.