This replaces most of the usage of @link-color in the UI with

var(--ink-p-link-color) and var(--ink-p-link-hover-color). These

give us consistent theme-friendly colors for links.
There are some instances that have not been replaced, but those will be

covered by larger changes.

Tested most of the links. There's still a lot of work involved for these

bits of the UI.