Add branding for cards based on project

[maxammann]

As a User I want to see see the branding of the current projec to the card.

Branding consists of two properties:

• color of card (bavaria is blue)
• Image

The branding get's selected based on the build config. We do not store the project currently in the card (protobuf). That means that based on the build config and the active project we select the branding.

The color and image should either be added to the build config theme or a separate entry like card-branding should be created.

WARNING: Only create a rough estimation of the following sketch! Do not spend more than 2h on implementing the design!

Acceptance Criteria:

• Cards can have different colors
• Colors are specified in the build config
• The image for the build config is specified in the build config

Technical Tasks:

• None, do it in this PR

[maxammann]

@maxammann add image of card