feat: port task execution summary (#5825)
### Description
This is a port of the `execution.go` module in `runsummary` that is used
by `execContext` via the `tracerFn` closure that gets passed back. In
the Rust version we instead communicate to the shared state via a mpsc
channel. This PR does not include the chrometracing functionality, but
that can easily be added as a responsibility of the state management
task.
Differences from Go:
I simplified the states that a task can go through compared to Go:
- `TargetExecuted`: This was used to mark when task execution finished
and was used for the time saved field in the cache. We will no longer
report the time that it takes to save outputs as part of the task
execution time in the run summary, but this can be added as an
additional state if desired later.
- `TargetInitialized`/`TargetBuilding`: initialized was only used for
the initial insertion into the map and building was the state that was
used once we confirmed that we had an actual task to run i.e. there was
a command attached to the task
- `TargetBuildStopped`: This state was never constructed in Go
In Rust there is now just:
- create a tracker
- "start" the tracker, this starts the timer
- move the started tracker to one of the finished states:
- canceled
- build finished
- build failed
- cache hit
I also completely removed the internal tracking of the various task
execution states, the tracker instead returns the state upon completion.
In Go, we never actually used the shared state except for when trying to
[find the partially constructed
summary](https://github.com/vercel/turbo/blob/main/cli/internal/runsummary/execution_summary.go#L228)
to add events to. We can completely avoid this since the tracker itself
is now the partially constructed summary.
### Testing Instructions
Unit tests
Closes TURBO-1273
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Co-authored-by: Chris Olszewski <Chris Olszewski>
