Implement latency commands

[prateek-kumar-improving]

Summary

Implement LATENCY HISTORY, LATENCY LATEST, and LATENCY RESET commands for both standalone and cluster clients.

Issue link

This Pull Request is linked to issue: #236

Features / Behaviour Changes

• latencyHistory(string $event): array|false — Returns latency spike time series for the specified event as an array of [timestamp, duration_ms] pairs. Returns
  empty array if event does not exist.
• latencyLatest(): array|false — Reports the latest latency events as an array of [event_name, timestamp, duration_ms, max_duration_ms] entries.
• latencyReset(string ...$events): int|false — Resets latency data for specified events (or all events if none specified). Returns the number of events reset.
• All three commands are available on both standalone (ValkeyGlide) and cluster (ValkeyGlideCluster) clients.

Implementation

• Added execute_latency_history_command(), execute_latency_latest_command(), and execute_latency_reset_command() in valkey_glide_commands.c
• All use STANDARD_METHOD_IMPL macro pattern
• LatencyLatest registered as zero-arg operation, LatencyHistory/LatencyReset as message operations in valkey_glide_core_common.c
• Uses process_core_array_result for history/latest and process_core_int_result for reset
• Cluster stubs use @see only per review conventions

Limitations

• PHPRedis does not have dedicated latency methods, so there is no PHPRedis signature to match. The API follows Valkey command semantics directly.
• Tests use rawCommand for CONFIG GET/SET to trigger latency spikes, as config() is not yet available on the cluster client. Issue link: Implement config command in cluster #284

Testing

Tests run in both standalone and cluster mode (inherited).

Checklist

Before submitting the PR make sure the following are checked:

• This Pull Request is related to one issue.
• Commit message has a detailed description of what changed and why.
• Tests are added or updated.
• CHANGELOG.md and documentation files are updated.
• Destination branch is correct - main or release
• Create merge commit if merging release branch into main, squash otherwise.