Bug 1686603 Part 2 - Add StyleSizeOverrides parameter to ReflowInput's constructor & co. to override data from style system data. r=dholbert

This patch adds the struct as a parameter to various functions.

The struct is cached in ReflowInput so that we don't need to pass it
down to the internal method where nsIFrame::ComputeSize() is called.

In the subsequent patches, we'll use it to revise the implementation of
flex container's flex base size resolution, and size overrides.

Differential Revision: https://phabricator.services.mozilla.com/D101793