Center align and change the background color for social links in menu drawer

[Ujjaval]

@Leonpojen
add below css into base.css file

.no-js details[open] > .menu-drawer, .js details[open].menu-opening > .menu-drawer, details[open].menu-opening > .menu-drawer__submenu {
    background-color: grey;
}
.menu-drawer .list-social {
    justify-content: center !important;
}