List per user notifications

[PeterDaveHello]

Not sure if you'd like to have this feature, just list all the notifications of my GitHub account, looks very useful to me :)

[henvic]

It would be cool and I would merge a pull request for that.

I shouldn't be able to work on this myself anytime soon.

[protoEvangelion]

Looks like this can be easily achieved with the newly added octokit api: https://octokit.github.io/rest.js/#octokit-routes-activity-list-notifications

For an example use the latest cmd: https://github.com/node-gh/gh/blob/c1f8cf2fea4961736c4f130af11f24983f4f90fb/src/cmds/notification.ts#L80

We could add a new flag like --list