Split off uw.DescriptionsDetailsWidget from UploadWizardDetails (and OOUI-ize)
This change converts the descriptions field to use OOjs UI, moving the
code to uw.DescriptionDetailsWidget and uw.DescriptionsDetailsWidget.
- uw.DescriptionDetailsWidget implements logic and UI for a single language and description pair. This code was previously scattered in mw.UploadWizardDescription, uw.model.Description and mw.LanguageUpWiz, all of which are removed now.
- uw.DescriptionsDetailsWidget implements logic for managing multiple descriptions and adding/removing them, which was mostly in UploadWizardDetails.
The dropdowns and text fields now use OOUI widgets and are aligned on one
line (as they used to be a long time ago, but this broke at some point).
Everything related to uw.model is also removed, since that attempt at
refactoring seems to have been aborted.
Some weird things that I noticed, but did not change:
- There is some questionably-looking logic changing some languages to others (now in uw.DescriptionDetailsWidget). I'm not sure how much of it is needed.
- 'descriptionlang' and 'description' URI query parameters are handled differently.