Pls add the variants ="inset" to the UDashboardSidebar. this way we can use the other design options easy for our dashboards. :)

### Package

v4.x

### Description

<template>
  <UDashboardGroup>
    <UDashboardSidebar />

    <slot />
  </UDashboardGroup>
</template>

### Additional context

_No response_