Add notification actions for stopwatch

[TheRupp]

Checklist

• [x] I made sure that there are no existing issues - open or closed - to which I could contribute my information.
• [x] I made sure that there are no existing discussions - open or closed - to which I could contribute my information.
• [x] I have read the FAQs inside the app (Menu -> About -> FAQs) and my problem isn't listed.
• [x] I have taken the time to fill in all the required details. I understand that the request will be dismissed otherwise.
• [x] This issue contains only one feature request.
• [x] I have read and understood the contribution guidelines.

Feature description

I wish that all notifications for a stopwatch have got notification "actions"/"action buttons". Which actions specifically? pause/resume, lap, reset

Why do you want this feature?

A user starts a stopwatch, then locks their phone. With those new notification actions a user could interact with the running stopwatch directly from the lock screen. This would save a little bit of time instead of opening the app.

Additional information

Related: #246