fix(ui-canvas): Proper iOS scale for bitmap cases

[CatchABus]

It seems that re-applying screen scale by default during setMatrix() call doesn't work well for all cases (e.g. bitmaps). This PR ensures setMatrix sets actual base values and developers can scale the canvas manually after the setMatrix() call. It's not perfect but this is what we already do in android canvas in order to scale pixels based on screen scale, so both platforms will have similar result.