Components: Popover uses top and left positioning hurting scroll performance

[corentin-gautier]

Using top and left positioning triggers a repaint of the area which could be avoided using transform : translate(x, y), improving performances (currently the scroll performances of the editor are not really good, even more when using fixed backgrounds)

gutenberg/packages/components/src/popover/index.tsx

Line 466 in df98b4b

left: Number.isNaN( x ) ? 0 : x ?? undefined,

Screen.Recording.2022-10-28.at.15.47.36.mov