[fix] pfe-navigation 1.x | position of caret on mobile menu item

[starryeyez024]

When there is no tray present, the alignment of the chevron is a bit too high:

Suggested: adjust the top property on the pseudo element

:host([is_nested]:not([has_tray]):not([parent_hidden])) .pfe-navigation-item__trigger::after {
    top: calc(var(--pfe-theme--container-spacer,16px) + 4px);
}

[bennypowers]

This should move to RHDS when it's established

[markcaron]

Will handle in RHDS version.
RedHat-UX/red-hat-design-system#375