fix(material-experimental/mdc-list): add selected indication in high contrast mode (#22447)
fix(material-experimental/mdc-list): add selected indication in high contrast mode (#22447)

When a list option is selected in single selection mode, it changes its background color to stand out. This doesn't work in high contrast mode so these changes port over the workaround that we have from the non-MDC list.
angular/components,mmalerba/material2,josephperrott/material2,DevVersion/material2,angular/components,mmalerba/material2,mmalerba/material2,crisbeto/material2,crisbeto/material2,angular/components,josephperrott/material2,DevVersion/material2,josephperrott/material2,DevVersion/material2,mmalerba/material2,josephperrott/material2,mmalerba/material2,angular/components,DevVersion/material2,crisbeto/material2,crisbeto/material2,josephperrott/material2,DevVersion/material2