Implement Disclosure Dropdown item content component
The following discussion from gitlab!108954 should be addressed:
- [ ] @afontaine started a [discussion](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/108954#note_1254564602): (+6 comments)
> @markrian sorry to ping you out of nowhere on this, but I see you've been working hard on `GlDisclosure`
>
> I am wondering if we can somehow simplify this slot-based API to remove some of the repetitive cruft? We're pretty much re-implementing `gl-tmp-dropdown-item-style` just to add a little pill. Note that this does not seem necessary for item [groups](https://gitlab-org.gitlab.io/gitlab-ui/?path=/docs/base-new-dropdowns-disclosure--default#groups)
>
> I'm sure there's some design decisions I'm missing context on, but would love to get your input here :smile:
issue