Add circuit breaker configuration support

[jeremyprime]

Summary

Add circuit breaker configuration support to the PHP client, matching the existing implementation in Java, Python, Node, and Go (valkey-io/valkey-glide#6050). The circuit breaker logic lives in the Rust core; this change adds the config array parameter, serializes it to protobuf, and surfaces a CircuitBreakerException type to callers.

Issue link

Closes #238

Features / Behaviour Changes

• New ?array $circuit_breaker parameter on ValkeyGlide::connect() and ValkeyGlideCluster::__construct()
• New CircuitBreakerException class (extends ValkeyGlideException) thrown when the circuit breaker is open
• Configuration keys: window_size_ms, failure_rate_threshold, min_errors, open_timeout_ms, count_timeouts, consecutive_successes
• All parameters optional with sensible defaults matching other clients

Implementation

• common.h: Added valkey_glide_circuit_breaker_config_t struct, constants, and plumbed into base config
• valkey_glide.c: Parse circuit breaker array, register exception class, cleanup on free
• valkey_glide_core_commands.c: Serialize config to ClientCircuitBreakerConfig protobuf message (field 30)
• valkey_glide_commands_common.h: Dispatch CircuitBreakerException when command_error_type == CircuitBreakerOpen
• Stubs and mock constructors updated for both standalone and cluster

Testing

• New unit tests added to ConnectionRequestTest.php:
  • testCircuitBreakerStandaloneDefaults: empty array uses defaults
  • testCircuitBreakerClusterDefaults: same for cluster
  • testCircuitBreakerStandaloneCustomValues: all fields customized
  • testCircuitBreakerClusterCustomValues: same for cluster
  • testCircuitBreakerNotSetByDefault: null when not provided

Checklist

• 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.

[currantw]

Reviewed to 7ba5343.

[currantw]

Reviewed to cec7239.
Looks good ✅
Thanks for replying to all my comments.
Will update C# GLIDE client to use a consistent approach.