Sign in with external provider
<%= form_for @conn, o_auth_path(@conn, :prepare_request), [method: "get"], fn f -> %>
<%= render @view_module, "_scopes.html", Map.put(assigns, :form, f) %>
<%= hidden_input f, :client_id, value: @client_id %>
<%= hidden_input f, :redirect_uri, value: @redirect_uri %>
<%= hidden_input f, :state, value: @state %>
<%= for strategy <- Pleroma.Config.get([:auth, :oauth_consumer_strategies], []) do %>
<%= submit "Sign in with #{String.capitalize(strategy)}", name: "provider", value: strategy %>
<% end %>
<% end %>