Add Image Mimetype format (e.g. WebP/Avif) & widht/height to rendering as configurable option

[JBlocks]

The Poster-Image uses the publicUrl, which renders the FAL without any ImageProcessing. To be able to configure the rendering and mimeType format and the width/height, there has to be a config option.

E.g. as Site Set or TypoScript

• media.video.poster.format = webp (webp, avif, jpg, ...)
• media.video.poster.width = 640c (optional or auto)
• media.video.poster.height = 480c (optional or auto)

The width and height currently depends on the f:media Attributes, but in some cases you would like to adjust the dimensions.