feat(provider): add Split.io Remote Config provider

[kirich1409]

Goal

Implement RemoteConfigValueProvider backed by Split.io.

Rationale

Split.io has a strong enterprise customer base for experimentation + targeting; consumers migrating from Split want first-party Featured support.

Scope

Split ships Android and iOS SDKs (no KMP). Split into two providers:

• providers:split-android — wraps io.split.client:android-client.
• providers:split-ios — wraps the Swift Split SDK via cinterop, exposed through a Kotlin facade.

Treatment values map to String/enum; numeric / boolean variants must be parsed via TypeConverter. Document this in the module README.

References

• Interface: core/src/commonMain/kotlin/dev/androidbroadcast/featured/RemoteConfigValueProvider.kt
• Android-only reference: providers/firebase/

Definition of Done

• New module(s) under providers/ published to Maven Central
• Unit tests with mocked Split client
• Sample wiring
• Wiki Providers page updated
• CHANGELOG.md [Unreleased] entry
• ./gradlew spotlessCheck && ./gradlew check clean