Limit available blocks templates in extranets (#2700)

app/models/communication/block/template/call_to_action.rb

app/models/communication/block/template/contact.rb

app/models/communication/block/template/datatable.rb

app/models/communication/block/template/definition.rb

app/models/communication/block/template/feature.rb

app/models/communication/block/template/key_figure.rb

app/models/communication/block/template/license.rb

app/models/communication/block/template/link.rb

app/models/communication/block/template/organization.rb

app/models/communication/block/template/person.rb

app/models/communication/block/template/sound.rb

app/models/communication/block/template/testimonial.rb

app/models/communication/block/template/timeline.rb

app/views/admin/communication/blocks/new.html.erb