Make task status service aware of current user

[DavidBiddle]

What problem does this pull request solve?

Trello card: No card for main change, but also includes https://trello.com/c/TVN9BNxQ/3448-refactor-formtaskstatusservice-to-use-dependency-injection

Passes the current user to the task status service. This follows the work in #2745 so that the task statuses are consistent everywhere.

This resolves an issue we were seeing where:

• the Welsh translation page had a non-gov.uk email address which matched the user's domain
• the page as a whole was valid and marked complete
• but the task in the task list was still showing as 'In progress'
• the form could not be made live.

Also includes a factory change to make testing Welsh forms easier (cherry-picked from #2717)

Things to consider when reviewing

• Ensure that you consider the wider context.
• Does it work when run on your machine?
• Is it clear what the code is doing?
• Do the commit messages explain why the changes were made?
• Are there all the unit tests needed?
• Do the end to end tests need updating before these changes will pass?
• Has all relevant documentation been updated?

[stephencdaly]

Changes look good and the bug is fixed.

Do you reckon it's worth adding a test for the scenario where the user enters a non-government email in the Welsh translations to check that the validation passes to prevent a regression?

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[DavidBiddle]

@stephencdaly good shout, I've added a test for that now