Backport worker_may_ignore history handling

[d2army]

Summary

• Backport worker_may_ignore history handling from the 0.1.x line to transfers-master / 0.0.x without proto regeneration.
• Make History::Event constructable when a history event has an attributes oneof unknown to the old generated proto, so worker_may_ignore can still be read.
• Ignore known Nexus/options-updated events and unknown worker-ignorable events while preserving fail-closed behavior for non-ignorable unknown events.

Why (#1)

• Temporal Cloud can attach new Nexus/options-updated history events that older 0.0.x Ruby workers do not understand.
• On the 0.0.x line, History::Event#extract_attributes can receive nil for an unknown attributes oneof and raise before worker_may_ignore is read; making attribute extraction nil-safe keeps the compatibility bit reachable.

Why (#2)

• StateManager#apply_event calls History::EventTarget.from_event(event) before its event-type case statement, so unknown event prefixes can raise before the final unsupported-event branch is reached.
• This backport adds the upstream ignore paths for known safe event types and for unknown events marked worker_may_ignore=true, while still raising for unknown events that are not explicitly safe to ignore.

Temporal team confirmation

Confirmed with the Temporal team that the relevant server-injected event types (WORKFLOW_EXECUTION_OPTIONS_UPDATED, WORKFLOW_EXECUTION_PAUSED, WORKFLOW_EXECUTION_UNPAUSED, WORKFLOW_EXECUTION_TIME_SKIPPING_TRANSITIONED, and the two server-injected NEXUS_OPERATION_CANCEL_REQUEST_* events) carry worker_may_ignore=true consistently, including in existing histories. This makes the runtime-only patch sufficient — the worker_may_ignore rescue path handles them via the same flow upstream PR #355 uses, and proto regeneration is not required.

Test plan

• RBENV_VERSION=3.0.6 bundle exec rspec -r temporal/connection/grpc spec/unit/lib/temporal/workflow/history/event_spec.rb spec/unit/lib/temporal/workflow/state_manager_spec.rb
• RBENV_VERSION=3.0.6 ruby -c lib/temporal/workflow/history/event.rb && RBENV_VERSION=3.0.6 ruby -c lib/temporal/workflow/state_manager.rb && RBENV_VERSION=3.0.6 ruby -c spec/unit/lib/temporal/workflow/history/event_spec.rb && RBENV_VERSION=3.0.6 ruby -c spec/unit/lib/temporal/workflow/state_manager_spec.rb && git diff --check