Refactor Translation Job creation

See: https://github.com/cftp/babble/commit/72abfa1ccd1dd21bff655ac94130db856f21dde3#commitcomment-4127854

When the user clicks on the "Edit Post" button in the admin bar, rather than creating a Job then redirecting on the `load-*` action for the post edit screen, we should amend the URL for the "Edit Post" button to create the job; e.g. link to the new translation job URL and pass params for the original post.

Read the linked commit and its comment first, then trace the admin-bar "Edit Post" link and the post edit screen's load-* action. Identify where the translation job is currently created and how the original post parameters reach the edit screen. Done means the link targets the new translation job URL, creates the job with the original post, and no longer creates it in the load-* action.

Written by the indexing model from the issue text.