Replace bitmaps with SVG images

[andersmelander]

SVG images are a requirement for Light mode/Dark mode and custom color palettes because we need the color of the glyphs to adjust to the current color palette.

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This issue is a requirement for #30 and #26.

[birbilis]

Can try Ethea's SVGIconImageList from GetIt (repo: https://github.com/EtheaDev/SVGIconImageList)

[andersmelander]

@birbilis The DevExpress TcxImageList that I'm already using supports SVG so there's no reason to introduce another dependency.

This task more has to do with replacing the existing bitmaps in the imagelist with SVG images.