New setting to select a command to be triggered when tracker stops

[lucaslopes]

This might be useful to automate some routines that are triggered every time the tacker registers a new entry.

In my particular case, I'm developing a plugin that works with the ObsidianSimpleTimeTracker plugin, which needs to be updated every time a new time track entry is registered.

[Ellpeck]

Hi, this is a nice idea!! I haven't had the time to work on the plugin recently, but I'll review this PR as soon as I get back to working on it :)

[lucaslopes]

Thanks! I ended up finding a way to do the functionality with your original plugin without needing my pull request. But feel free to incorporate it if you find it useful to integrate with other plugins.

[Ellpeck]

Oh, that looks like a pretty good solution on your part for now!

I think if it's just about plugin compatibility, rather than exposing something like this for users to use for "custom" integrations, it might be nicer for me to provide an event as part of the plugin api (which you can access a very similar way through the obsidian api too). Maybe something like an onTimeTrackerChanged event or something similar. I'll think about it though! :)