Support vector-effect="non-scaling-stroke"

[timohausmann]

Sometimes it's wanted to exactly define the strokeWidth and prevent it from upscaling, for example large chevrons for navigation.

Currently, the larger the size, the bolder the stroke. Currently to get a 1px stroke for a 48 size I have to calculate the stroke width based on the 24 size:

<ChevronDown size={64} strokeWidth={1/(64/24)} />

What would be nice:

<ChevronDown size={64} strokeWidth={1} nonScalingStroke />