[Branding] Extend Theme::overrideServerUrl() to allow a list of predefined URLs

[SamuAlfageme]

There's this one use-case where an organization might have multiple ownCloud instances for different aspects/departments: to keep things semantically separated, see them as independent services, etc.

The multi-account support on the client allows users to sync from various locations with the same client. However, companies normally need something in the middle: flexible to add more than one account but restricted to their internal instances.

Instead of providing one branded client with a predefined URL for each of these instances, It'd be much more powerful to allow the user to select one from a list at account-creation time. I made some mockups to throw some light on how this could look like:

With Headings	Just the URL

This list of URLs would be fetched from ownBrander (we'll require to do something similar for the iOS app in the near future: https://github.com/owncloud/ownbrander/issues/769):

{
	"Internal ownCloud": "https://cloud.company.xyz",
	"Sales ownCloud": "https://sales.company.xyz",
	"Customers ownCloud": "https://customers.company.xyz"
}

... and fit in the generated *-theme.h.

Also, consider greying-out / disabling those unreachable URLs when facing the selection:

cc/ @michaelstingl - we discussed this one last time in NUE - maybe it also makes sense for the rest of the platform?

[guruz]

(For the record: We also have/had a feature where there is a lookup/mapping from username->oC_URL.
However that might not be good here as one would have the same username on all thos instances)

[ogoffart]

What would be easy to do would be to replace the lineedit in which one need to enter the URL, with a combobox.
We could need a new Theme::predefinedServerUrl() which returns a QStringList. Or a list of a pair with a Url, and a better description (but this can be a problem for translations)

Having push buttons, or radio buttons would be possible too.

[ogoffart]

@pmaier1 Is this still something that needs to be done?

[michaelstingl]

no priority for now