* feat(pubsub): read exactly once for SubscriptionProperties

* rename vars to be specific this is exactly once delivery

…to pubsub-exactly-once

…oogleapis#6157 (googleapis#6162)

* add RWMutex for guarding exactly once bool

* feat(pubsub): send stream ack deadline seconds on exactly once change

* remove extra test

…apis#6201)

* add AckResult and related methods

* feat(pubsub): add AckWithResult and NackWithResult to message

* feat(pubsub): add AckWithResult and NackWithResult to message

* add comments for AckResult and bring over AcknowledgeStatus from internal

* update function definition for IgnoreExported in tests

* temporarily update internal/pubsub for samples test

* change enum naming to AcknowledgeStatus

* remove extra enums in temp internal message.go

* remove internal/pubsub/message.go

* fix style issues with variadic function options

* add back comment format to exported const

* keep track of AckResults if exactly once is enabled

* add AckResult and related methods

* feat(pubsub): add AckWithResult and NackWithResult to message

* feat(pubsub): add AckWithResult and NackWithResult to message

* add comments for AckResult and bring over AcknowledgeStatus from internal

* update function definition for IgnoreExported in tests

* temporarily update internal/pubsub for samples test

* add process results

* change enum naming to AcknowledgeStatus

* remove extra enums in temp internal message.go

* remove internal/pubsub/message.go

* add process results

* update process info with new enum names

* add tests to process error info

* add process results

* update process info with new enum names

* add process results

* add tests to process error info

* clean up iterator from merge

* cleanup comments

* add list of retriable errors to test

* simplify testing of completed/retry slice lengths

* remove getStatus/ackErrors methods

* address code review comments

* remove error string conversion step

* refactor sendAck to pipe errors to AckResult map

* rewrite sendAck/sendModAck for exactly once

* add AckResult to list of uncompared methods

* use ackResultWithID in all locations

…to pubsub-exactly-once

* retry acks in goroutine

* retry acks/modacks with transient errors

* add retry test

* add nack tests and support shorter timeouts

* add integration tests

* remove extra comment

* add commnets to ack/modack methods in iterator

…gle-cloud-go into pubsub-exactly-once

…d-go into pubsub-exactly-once

…_test

…d-go into pubsub-exactly-once

…d-go into pubsub-exactly-once