fix: Include an error code in provider error events

[kinyoklion]

Requirements

• I have added test coverage for new or changed functionality
• I have followed the repository's pull request submission guidelines
• I have validated my changes against all supported platform versions

Related issues

OFP requirement 5.1.5 (sdk-specs OFP-openfeature-provider-behavior): PROVIDER_ERROR events SHOULD populate the event details' error code.

Describe the solution you've provided

When the LaunchDarkly data source transitions to OFF, the emitted PROVIDER_ERROR event details now include ErrorCode.GENERAL alongside the existing message:

emitProviderError(ProviderEventDetails.builder().message(message).errorCode(ErrorCode.GENERAL).build());

Added LifeCycleTest.itIncludesAnErrorCodeInErrorEvents.

Describe alternatives you've considered

A more specific code (e.g. PROVIDER_FATAL for 401/403) was not used; OFP does not define a mapping, and the Python provider already uses GENERAL for the same transition. Choosing per-error codes would be a cross-SDK decision.

Additional context

OpenFeature Java SDK 1.23.0 fixed propagation of errorCode from provider event details to handler EventDetails, so handlers now observe this value.

Link to Devin session: https://app.devin.ai/sessions/929f5530882d40bc95e55391e97536d5
Open in Devin Desktop: https://app.devin.ai/desktop/session/929f5530882d40bc95e55391e97536d5?variant=devin
Requested by: @kinyoklion

SDK-3254

[devin-ai-integration]

I'll fix CI failures and address comments from users with write access. I'll skip comments containing "(aside)".

• Disable automatic comment, CI, and merge conflict monitoring