Cation adds api-review/requested when PR is labeled with api-review/reviewed

[itsananderson]

This PR illustrates the problem: https://github.com/electron/electron/pull/40301

When an API WG member has reviewed a PR and added feedback, I think we're supposed to add the api-review/reviewed label and remove the api-review/requested label. However, when we do that it looks like Cation automatically adds back the api-review/requested label (which triggers API WG notifications about a new PR).

If I'm understanding our API WG labeling system correctly, Cation should only be adding the api-review/requested label if no other api-review label (including api-review/reviewed) has been applied.

[dsanders11]

Is api-review/reviewed a new label that's been created recently? It's not one of the labels that cation knows about.

https://github.com/electron/cation/blob/b5ea25ad6ebfb0f4faa3169089d94ea9c228bdb6/src/constants.ts#L37-L41

cation doesn't let humans modify those labels on a PR, since that would sidestep things. If you want to add api-review/reviewed as an intermediate state between requested and approved/declined, the logic in this repo will need to be updated.