Popover need "footer" slot

[pizberg]

This function solves the problem (这个功能解决的问题)

There is only header slot in N-Popover, but there are needs of both header and footer slots sometimes.
Or, is there any simple way to implement both header and footer with same dividers, like in N-List?

Expected API (期望的 API)

<template #footer>
balabala