Add EventTypeTransferOpFailed for token transfer operations that fail

[awrichar]

Part of #218.

This basically works, but I'd like to vet the behavior since there are some slight inconsistencies.

When you submit a transfer request, you'll (now) ultimately receive one of two events in response:

• EventTypeTransferConfirmed if transfer is confirmed -> references the transfer's LocalID so you can look up the transfer
• EventTypeTransferOpFailed if transfer fails -> references the operation's ID so you can look up the failed operation (there is no transfer object created in this case)

Even though this means the events are a bit asymmetric, I can't come up with a more sensible way to do it.

However, when submitting a transfer with confirm=true, the sync-async bridge tracks a single ID which will ultimately resolve in success or failure. I've chosen the transfer's LocalID, but that means there's an additional step in the case of EventTypeTransferOpFailed, for sync-async to map the operation ID to the transfer LocalID. This also meant extracting some helpers to txcommon (for lack of a better place to put them).

[codecov-commenter]

Codecov Report

Merging #279 (d28bc53) into main (bce659a) will decrease coverage by 0.26%.
The diff coverage is 32.65%.

❗ Current head d28bc53 differs from pull request most recent head 819ef6f. Consider uploading reports for the commit 819ef6f to get more accurate results

@@             Coverage Diff             @@
##              main     #279      +/-   ##
===========================================
- Coverage   100.00%   99.73%   -0.27%     
===========================================
  Files          223      224       +1     
  Lines        12374    12395      +21     
===========================================
- Hits         12374    12362      -12     
- Misses           0       32      +32     
- Partials         0        1       +1     

Impacted Files	Coverage Δ
internal/assets/manager.go	100.00% <ø> (ø)
internal/events/operation_update.go	75.00% <0.00%> (-25.00%)	⬇️
internal/txcommon/token_inputs.go	0.00% <0.00%> (ø)
pkg/fftypes/event.go	100.00% <ø> (ø)
internal/syncasync/sync_async_bridge.go	89.84% <37.50%> (-10.16%)	⬇️
internal/assets/token_transfer.go	100.00% <100.00%> (ø)
internal/events/tokens_transferred.go	100.00% <100.00%> (ø)
internal/orchestrator/bound_callbacks.go	100.00% <100.00%> (ø)
internal/tokens/fftokens/fftokens.go	100.00% <100.00%> (ø)

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[awrichar]

I've realized this is incomplete - there's still an issue when a transfer is accompanied by a message, because if the transfer fails, the message recipients will be waiting forever to receive it. Closing this until I can address that problem, since it may impact the shape of this change.