Add Spanish and Catalan translations

[fjorba]

To start with, translate the yaml files.

[fjorba]

Help file will come later.

Please note that if blacklight-locale_picker 0.3.1 is also installed and more than one language is defined the following error is raised:

[...]/vendor/bundle/ruby/2.7.0/gems/blacklight-locale_picker-0.3.1/app/views/shared/_locale_picker.html.erb where line #11 raised:

No route matches {:action=>"index", :controller=>"advanced", :locale=>:ca}

    def path(method_name)
      raise ActionController::UrlGenerationError.new(message, routes, name, method_name)
    end

I'm unsure where does it has to be fixed, here or in blacklight-locale_picker.

[fjorba]

Note to myself: may be fixed with https://github.com/projectblacklight/demo.projectblacklight.org/pull/37