v5: Dropdown - create a class/data-attribute selector to prevent closing dropdown-menu on click

[jakubmuda]

By default .dropdown-menu hides when you click inside it. The only exception is when you have a form - it stays open when you focus on input or click buttons. It would be good to have a dedicated class .dropdown-menu-something or data attribute data-something="something" to prevent .dropdown-menu from hiding for content other than forms.

<ul class="dropdown-menu dropdown-menu-something" aria-labelledby="dropdownMenuButton">

OR

<ul class="dropdown-menu" data-something="something" aria-labelledby="dropdownMenuButton">

It looks like the javascript for preventing such behaviour in forms is very simple so why not add another selector?
Line 634: https://github.com/twbs/bootstrap/blob/main/js/dist/dropdown.js#L634