Fill breakpointHitList of stopped events

[Stopped](https://microsoft.github.io/debug-adapter-protocol//specification.html#Events_Stopped) events can have an optional list of hit breakpoints.
This isn't filled at the moment.

Adding it enables the "[Wait for breakpoint](https://code.visualstudio.com/docs/debugtest/debugging#_conditional-breakpoints)" condition for breakpoints. But more importantly can give other extensions that track such events an essential hint for other custom behavior on breakpoint hits.

We should consider adding this, even if we would only report one breakpoint at a time instead of a full list.