Upload documents to google drive (UD3, UD6.1, UD6.2)

[Renny4Real]

This PR is the rebased form of #1302 and will replace it.
(Pushed the rebased branch to a separate branch to check that the rebase worked without losing our original work)

Cancel functionality has been broken out into a new ticket (TEVA-504)

Google drive issue has been documented in a separate ticket (TEVA-505)

Uploading progress indicator to be reviewed, amended and finalised (TEVA-506)

ACCEPTANCE (TEVA-408):

• Show users a list of documents they have uploaded
• While a file is uploading, I see a 'cancel' control
• The 'Save and continue' button is deactivated when files are uploading. It is reactivated when files have finished uploading
• If the file upload is complete, show the user the file size
• Once a file has finished uploading, its status shows as 'Uploaded'
• If the file upload is not complete, show the user an upload percentage indicator. Collective indicator of all upload steps.
• A happy path set of tests exist that ensures this interaction occurs
• The code has been peer-reviewed and approved by at least two other developers
• A running example of this workflow has been signed off by Product, UX
• The code is released to live

[tatyree]

Overall good, but needs a bit of work on a few small things. See comments.

[david-mears-2]

I wonder if there's a risk, in using a separate variable to track whether there are errors, that it will become decoupled from the actual state of @documents_form.errors which is partly determined by ActiveModel.

unless @errors 

could become (something like):

unless @documents_form.errors

in order to have a single source of truth about whether there are errors. Maybe this is just a pattern I'm unaware of though.

[Renny4Real]

I'm not sure, but I think this is because we don't validate whether we have a virus in the form model.
We wouldn't know if there was a virus unless Google tells us so the method is invoked depending on the response from Google.

[david-mears-2]

It looks like the error is created on line 84:

@documents_form.errors.add(:base, t('jobs.file_virus_error_message', filename: filename))

Does that count as validating in the form model, for your purposes?

[tatyree]