Support cancellations of ongoing invocations

[tillrohrmann]

The cancellation of ongoing invocations requires finding the leaf nodes of the call hierarchy starting at the to be canceled call. Cancelling these leaf nodes will trigger the running of their compensations and then the propagation of the cancellation upwards the call hierarchy.

The tasks here reflect the design described in this document: https://docs.google.com/document/d/14s7D6KP1IKNS1K3OrVbZNKGNei9TO_-9Sk0YC5mpht8/edit?usp=sharing

Mandatory tasks

Beta Give feedback

1. Cancellations service-protocol#52
   enhancement +1
   
2. Kill the complete call tree when killing an invocation #914
   4 of 4
   enhancement partition-processor umbrella +3
   
3. Cancel invocations by cancelling from the leaves #978
   7 of 7
   +0
   

We also track in this umbrella some followup tasks that complete the overall picture of the cancellation feature

Optional/followup tasks

Beta Give feedback

1. Scan the outbox for cancelled invocations that have not been delivered yet #917
   enhancement partition-processor performance +3
2. Kill/cancel invocation range/group #827
   admin opsex +2
3. CLI flow to cancel/kill invocations #924
   api-devex cli +2
4. Support killing of background and delayed calls #979
   +0

[slinkydeveloper]

Together with this issue, I think we can easily introduce a command like "cancel and restart", that will cancel and immediately restart the invocation, without losing the lock.

[slinkydeveloper]

I'm gonna work on a design document to implement this feature.

[slinkydeveloper]

Design document: https://docs.google.com/document/d/14s7D6KP1IKNS1K3OrVbZNKGNei9TO_-9Sk0YC5mpht8/edit?usp=sharing

[tillrohrmann]

All the mandatory tasks are completed.