Fix inconsistency with no ssh key message

Created by: atomaka

When a user has not added an SSH key, the alert message is inconsistent depending on if the project is empty or not.

Currently:

This update will fix the message to match the show action by passing it as content_for :flash_message. The result will be a more consistent look that has the additional space and appropriate link styling matching the non-empty project display.

app/views/projects/empty.html.haml

-.alert_holder
+= content_for :flash_message do
   - if current_user && can?(current_user, :download_code, @project)
     = render 'shared/no_ssh'
     = render 'shared/no_password'