feat(android-foreground-service): add ability to define notification channel options

[DoctorMcKay]

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Close #266

Adds a new createNotificationChannel method which allows implementing apps to create a notification channel prior to starting a foreground service. If a channel is not explicitly created, it's created with the same default values as previously when startForegroundService is called.

[robingenz]

Thank you for creating this PR! Please just copy the implementation from the Capacitor Firebase Messaging plugin, see https://github.com/capawesome-team/capacitor-firebase/blob/42d77fecca3871b910ac809bf1d14ff0c60dd762/packages/messaging/src/definitions.ts#L117

You can keep the method name createNotificationChannel. You would also need a deleteNotificationChannel method.

[github-actions[bot]]

It looks like there hasn't been a reply in 30 days, so I'm closing this issue.