refactor: observability sdk

[mario-launchdarkly]

Note

Rearchitects the SDK into modular services (logs/traces/metrics/session/crash) using OpenTelemetry exporters and new domain models, adds sampling and URLSession instrumentation, and replaces legacy modules and wiring.

• Architecture:
  • Split into DomainModels, ApplicationServices, OTelInstrumentation, ObservabilityServiceLive, iOSSessionService, and KSCrashReportService targets; remove legacy Observability, Instrumentation, and API/Observe layers.
  • Reorganize Package.swift to reflect new modules and tests.
• Core APIs:
  • Introduce domain types: AttributeValue, Severity, Span, Metric, and updated SemanticConvention.
  • Add service facades: ObservabilityService (aggregates MetricsService, TracesService, LogsService), SessionService, UserInteractionService, CrashReportService with async flush.
  • Redesign Options (feature flags for logs/traces/metrics, tracingOrigins, urlBlocklist, customHeaders as dict, OSLog).
  • Update LDObserve to use ObservabilityService with concurrent access and async flush.
• OTEL Instrumentation:
  • Implement HTTP exporters for logs/metrics/traces, sampling decorators, and resource propagation; add URLSession instrumentation and span customization.
  • Add user interaction spans (user.tap, user.swipe).
• Crash Reporting:
  • Replace old crash reporter with KSCrashReportService and LDCrashFilter that emits fatal logs via LogsService and awaits async flush.
• Sampling:
  • Refactor sampler into SamplingLive (ExportSampler.build/customSampler), add helpers to sample logs/spans and propagate launchdarkly.sampling.ratio attribute.
• LaunchDarkly integration:
  • Observability plugin builds ObservabilityService, enriches resource and headers with launchdarkly.sdk.version and highlight.project_id.
  • EvalTracingHook now starts/ends spans via LDObserve.
• Example App/Views:
  • Adjust imports; TraceView ends span and triggers LDObserve.shared.flush(); config uses new Options flags.

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[abelonogov-ld]

There are small comments but they could be fixed later