* DIsplay missing stock owners banner
* Extract the helpdesk url constant
* Add test, fix copy order
* Display banner to support
* Hide duplicate logs banner if other banners are present
This renames the case_log to lettings_log as everything we've written so
far has been geared towards lettings of social housing so it makes sense to
have the name describe this. This is also a precursor to adding in stuff for
sales logs (whatever shape that takes)
Co-authored-by: James Rose <james@jbpr.net>