Add ability to brand infrastructures / cloud profiles

[dhague]

What would you like to be added: Gardener Dashboard currently has a built-in set of vendors, names and logos that cannot be customized. To help users identify the correct infrastructure and for emphasize (internal) brand names, it would be good to be able to configure the appearance in the Gardener Dashboard.

Example use case: Instead of using an OpenStack logo for SAP Converged Cloud clusters, please use this logo:

Users may be confused when using SAP Converged Cloud to see this labeled as "OpenStack". For SAP-internal demos this is especially confusing.