Add some more filters

[NotMephisto]

A blend filter can be added to mix colors that are already present.

For example, by taking background and primary or instead of primary you can take source color to get an accent background. This filter can give a little more possibilities to implement colors or you can make accent background, so that it generates it based on the colors that are already there

[NotMephisto]

It will be easier to use blend with template files, for example like this

@define-color background {{ colors.background.default.hex | blend = {{ colors.primary.default.hex }} }};

So that it generates that color immediately without having to put it into config.toml

[InioX]

I'll look into it after I add adjust_hue, grayscale, and invert