Adds an `IsSuspended` field to `AsyncTaskInfo`, which is the same value
as `HasTaskDependency`, but uses the `Is<State>` naming to match
`IsEnqueued`, `IsRunning`, and `IsComplete`.
Based on the docs in Task.h:
```cpp
/// A task can have the following states:
/// * suspended: In this state, a task is considered not runnable
/// * enqueued: In this state, a task is considered runnable
/// * running on a thread
/// * completed
```
rdar://148663671
When the RunJob pointer is set to adapters, we try to get the "real" run pointer from the context. However, there are cases where the context can be a dangling pointer, when the task has finished with it but hasn't reset the pointer to anything else. For cases where that can happen, the context is legitimate only when there's a dependency record. Check for a dependency record before trying to read the context in those cases.
In most uses this will fail gracefully or return a garbage run pointer, but swift-reflection-test uses an in-process memory reader which can crash when trying to chase this pointer, resulting in test failures.
rdar://149252404
Iterating child tasks depends on knowing the size of AsyncTask, and changing the size of the task broke it. Instead of relying on mirroring the full structure in our out-of-process definitions, add a debug variable to libswift_Concurrency that contains the size of AsyncTask.
While we're there, add some more validation to child task enumeration. Check each child task's metadata pointer to make sure that it actually points to the AsyncTask metadata, and have the inner loop also increment and check ChildTaskLoopCount to stop runaway iteration in that loop.
The definition of `DefautlActorImpl` changed in https://github.com/swiftlang/swift/pull/73998. This change reflects those changes on to RemoteInspection's platform independent definition.
