refactor(v-tabs): added default theme background
refactor(v-tabs): added default theme background

changed `v-tabs-bar` to have a default color to match that of `v-card`

Webifi/vuetify,vuetifyjs/vuetify,Phlow2001/vuetify,KaelWD/vuetify,azaars/vuetify,vuetifyjs/vuetify,Webifi/vuetify,vuetifyjs/vuetify,azaars/vuetify,Phlow2001/vuetify,KaelWD/vuetify,Phlow2001/vuetify,KaelWD/vuetify,Phlow2001/vuetify,vuetifyjs/vuetify,Webifi/vuetify