feat(push-notifications): add unregister functions

[markemer]

Closes: #1100, Related to PR #1110 which this supersedes. We can close that PR when this merges.

[jcesarmobile]

The new method needs to be added to the plugin interface in the definitions.ts file
https://github.com/ionic-team/capacitor-plugins/blob/main/push-notifications/src/definitions.ts#L31

And also run npm run build so the method appears in the plugin docs

And would be good if the test app gets updated with a new button on the push notifications page to call the unregister method

[markemer]

The new method needs to be added to the plugin interface in the definitions.ts file https://github.com/ionic-team/capacitor-plugins/blob/main/push-notifications/src/definitions.ts#L31

And also run npm run build so the method appears in the plugin docs

And would be good if the test app gets updated with a new button on the push notifications page to call the unregister method

Duh, yeah - I knew a forgot something - I was so preoccupied with thinking I forgot something on the native side, I forgot all the typescript.