Introduce Font Zoom for HDR displays

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Some users on 4K/8K monitors report very tiny fonts in Meile. This is due to fonts being rendered for 1080p. There should be a setting in Settings that adjusts font zoom, i.e., 110%, 120%, etc.

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I'm currently unsure how to achieve this. Any input is certainly welcomed. Adding a bounty to this as it does not need to be prioritized for 2.0.0

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I think I just need to use "sp" instead of "dp" for fonts.