feat: Cache and reuse registry data across rounds

[alin-at-dfinity]

Cache previously read registry values (NetworkTopology, OwnSubnetInfo and RegistryExecutionSettings) along with the registry version they were read at. On the next registry read (during the next execution round), if the same registry version is requested, return the cached values.

Reading the registry is now about 50% of the (admittedly already low) DSM overhead (~20 ms of a total ~40 ms; which is still 10% of the average 400 ms round).

[zeropath-ai]

✅ No security or compliance issues detected. Reviewed everything up to 0ee310e.

Security Overview

• 🔎 Scanned files: 4 changed file(s)
• 🔗 Scan Link: https://zeropath.com/app/repositories/f5e9d2bb-29a4-4b64-902a-391d65fd8b2d?scanId=950573da-c5e8-4cd7-a474-f4ef443a46e5&codeScanTypes=PrScan&tab=issues

Detected Code Changes

Change Type

Relevant files

Enhancement

► rs/messaging/src/message_routing.rs     Introduce RegistryReader with caching of registry data and Arc-based data sharing ► rs/messaging/src/message_routing.rs     Replace direct registry reads with RegistryReader in BatchProcessorImpl ► rs/messaging/src/message_routing.rs     Add CachedRegistryData structure and RegistryReader methods ► rs/messaging/src/message_routing.rs     Update BatchProcessor and tests to use RegistryReader ► rs/messaging/src/message_routing/tests.rs     Update tests to utilize RegistryReader in various scenarios ► rs/messaging/src/state_machine.rs     Switch StateMachine to use Arc and Arc types in signatures ► rs/messaging/src/state_machine.rs     Update implementation to assign Arc values directly ► rs/messaging/src/state_machine/tests.rs     Adjust test fixtures and assertions for Arc-based topology/types ► rs/messaging/src/message_routing/tests.rs     Adjust tests to call RegistryReader.read_registry and .try_to_read_registry via new interface ► rs/messaging/src/message_routing/tests.rs     Extend tests with caching behavior verification for RegistryReader