[async][test-loop] Improve error handling

Test: successful compilation
Bug: ZX-2613 #comment

Change-Id: I830567ae520382480631acef41bd6fe8a879a175

Revert "[async] Use fbl::DoublyLinkedList in TestLoopDispatcher"

This reverts commit 764b403247be7015a8b9a5e22180d100f4cdb96f.

Reason for revert: https://fuchsia-review.googlesource.com/c/garnet/+/185561
Is causing PlayerTest.FakeSegments to time out for some reason.

Original change's description:
> [async] Use fbl::DoublyLinkedList in TestLoopDispatcher
>
> Use C++ fbl::DoublyLinkedList instead of the C listnode library.
>
> Tested: affected tests pass.
> Change-Id: I3545da3738b9f6559d714f6cef2307ab421d3b7a

TBR=jeffbrown@google.com,joshuaseaton@google.com

Change-Id: Ie817ec314bf0d7f89d54fb78cf5cba8520715776
No-Presubmit: true
No-Tree-Checks: true
No-Try: true

[async] Use fbl::DoublyLinkedList in TestLoopDispatcher

Use C++ fbl::DoublyLinkedList instead of the C listnode library.

Tested: affected tests pass.
Change-Id: I3545da3738b9f6559d714f6cef2307ab421d3b7a

[async] Add TestLoopDispatcher::HasPendingWork().

-The logic of TestLoop::RunUntil() is simplified.
-Moreover, this method will be an asset in the move towards
using multiple dispatchers: it greatly simplifies the logic of time
advancement to know when the set of dispatchers collectively has no
more work to do.

Tested: all tests in the peridot kitchen sink run successfully.
Bug: LE-472
Change-Id: Idd69da9707297106cd1f6c0ffa0eb1e9270afbd3

[zx] Remove zx_handle_t overload of zx::port::cancel().

Bug: ZX-2310
TEST=CQ
Change-Id: Ibb8c4c3459066bb83753472b2801c6a7684f48a4

[async] Make time external to TestLoopDispatcher.

This change sets the stage for the creation a 'multi-queue' loop
that manages multiple dispatchers with a shared sense of fake time.

Moreover, dispatching is made more fine-grained: waits and tasks
are now dispatcher one a time.

Tested: all tests (Topaz and down) pass.
Bug: LE-472

Change-Id: Ic254dbaf0c9b05fc16080f3a504eed23f65349cc

[zx] Switch port::cancel() to accept container rather than raw handle.

Bug: ZX-2310
TEST=CQ
Change-Id: Ib95fc4a6da1a1e9aef8a86cb9bcee39044c9cbb2

[async] Fix bug in TestLoopDispatcher::CancelWait

CancelWait() was not checking to see if a wait was in the list of stored
waits before deleting it.

Change-Id: I921206396e9910baaa751cb1b396968f353a78f6

[syscalls] Remove count arguments from port_queue and port_wait

This argument is not used and always must be one. I tried implementing
some reasonable behavior for this parameter on port_queue, but it wasn't
clear what to do when we encounter an error during the queue operation
because there isn't an out parameter for how many we succeeded in
queuing.

Rather than having a half-baked feature, we should just remove the
parameter and add another function that does vectorized versions of
these operations if we need that in the future.

Change-Id: Ifffcd6d705442cc830912a67c8117ffe5ec8295d

[async] Update async::TestLoop API

-Introduce RunFor() and RunUntil()
-Return booleans instead of zx_status_t which give whether work was done
during a Run* call.
-While dispatching tasks, progressively advance the fake clock.

BUG: ZX-1819
Change-Id: Ia3f8b47a10610492eb0e336aa0df65e74f6a38a6

[zx] Call zx_port_{wait,queue} with correct count

In the near future zx_port_{wait,queue} will not accept a count of zero.
Change all zircon callers to call these functions with a count of one.

ZX-1291 #comment

Change-Id: I5697208c7931a5e117f469c901c78f65615eeee0

[async] Tidy up the libasync API futher.

Deleted WaitWithTimeout since it is no longer used.
Removed flags and reserved storage.
Removed return code from wait handler.
Removed *_or_report_error variants after further consideration.
Deleted the non-RAII variants of the C++ wrappers; these wrappers
might as well be safe to use. Clients desiring minimum overhead
can use the C API instead if they prefer.
Made the C++ wrappers more systematic; each one has a fbl::Function
and a Method based variant.
Added a C++ wrapper for Tasks which takes a no-arg closure.
Improved consistency across all async operations, including docs.
Ported all programs to the new API as required.
Beefed up the tests.

Change-Id: I97beca26cec6d94fa7efd282c8d2620cdbcb84e5

[async] Tidy up the libasync API for tasks and receivers.

Remove flags fields and reserved storage.
Make the C++ wrappers friendlier.
Move the ops invokers into libasync.a itself in preparation for
adding versioning to the ops structure.
Add *_or_report_error() function variants which make it easier
to systematically handle errors while posting tasks or
enqueuing packets.
Removed the return value from task handlers to reduce confusion
around the lifetime of the task structure and remove an
unusual error handling scenario in case of a failure to
schedule a task to be repeated.
Pass the Task* to the handler for consistency with the C API.
Added some missing static library dependencies.
Reduce use of libfbl (except fbl/function.h).
Remove uses of private inheritance.

Change-Id: I7ccea5b68d6bccb2c7a236d112428c9b17fe8cdd

[async] Move AsyncStub to lib/async-testutils

Change-Id: Id05d08eaafc48c8778039e4c17b28186554ed90f

[async] Introduce a test async_t implementation with fake time.

Unit tests included.

BUG: ZX-1819

Change-Id: I808eef9360873ec882bdffcd9020006679925f9e