`StateLabel` should support "closed as not planned" state for issues

[anleac]

Describe the bug
Component at hand: https://primer.style/react/StateLabel

To support the new feature that is in GitHub, we should support a "closed as not planned" status for issues.

Example: https://github.com/anleac/blank_public_repo/issues/3

The new way of closing the issues has a different colour, and icon, and we should support this as another state option, perhaps with a name of issueClosedNotPlanned (for example)

The colour should be: rgb(110, 118, 129)
and icon: octicon-skip

Expected behavior
We have another state choice option, which would represent a grey closed status with the correct icon.

Screenshots
Above.

Desktop (please complete the following information):
All environments.