Add support for images with various qualities

[defagos]

As a developer integrating Pillarbox I might need higher or lower resolutions for artworks retrieved by Pillarbox. Currently a single resolution is supported but on small / large layouts this might be superfluous or insufficient.

Hints

• We could simply turn current image sources into arrays of sources with various qualities (optional), then have lazy retrieval be made for some desired quality (parameter added to image retrieval, a func instead of a prop). Or maybe have a parameter added to image sources for an image size.
• We could also provide a format (1:1, 16:9).
• Internal usage (e.g. Control Center) would request one of the qualities.
• Maybe an ImageCatalog type would provide for better encapsulation.
• Qualities should likely be loosely defined (maybe low, medium and high) with recommended resolutions. We should probably also have sensible fallbacks when some image is requested but the corresponding source is missing.

Acceptance criteria

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Tasks

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