Limit fileuploadjob concurrency (#326)

Author: dcollie2

app/jobs/file_upload_job.rb

@@ -1,4 +1,6 @@
 class FileUploadJob < ApplicationJob
+  limits_concurrency key: ->(language_id, *args) { language_id }
+
   def perform(language_id, file_id = nil, provider_id = nil, share = ENV["AZURE_STORAGE_SHARE_NAME"])
     @language = Language.find(language_id)
     @processor = LanguageContentProcessor.new(language)