feat: Enable Web support (JS/Wasm) for multiplatform-settings-datastore

[terrakok]

Motivation

Starting in recent versions, Google has released Web-compatible artifacts for Jetpack DataStore:

• androidx.datastore:datastore-core-wasm-js
• androidx.datastore:datastore-preferences-core-wasm-js
• androidx.datastore:datastore-core-okio-wasm-js (likely using Okio for cross-platform IO)

Currently, the multiplatform-settings-datastore module is restricted to non web platforms. However, since the underlying DataStore library now supports Web (via Okio/Wasm), multiplatform-settings should be able to expose this functionality.

Proposed Solution

I propose updating the multiplatform-settings-datastore module to include JS and Wasm targets.

Since multiplatform-settings acts as a wrapper around androidx.datastore, it should be sufficient to:

1. Add the wasm-js and js artifacts from the androidx.datastore ecosystem to the module's dependencies.
2. Ensure the backend configuration allows these targets to use the Okio-based implementation.

This would allow Web developers to use the type-safe ProtoBuf API of DataStore, just like Android/iOS and Desktop developers, without needing to switch to the basic Key-Value preferences module.

Why this is needed

Web developers currently lose the benefits of Protocol Buffers and Flow-based reactive streams when using multiplatform-settings. By leveraging the new Google Web artifacts, we can provide a consistent API across all platforms (Android, iOS, Desktop, Web).

Additional context

If the current implementation relies on file-based storage, the new okio-wasm-js artifacts seem to provide the necessary abstraction to make this work on Web (likely mapping to IndexedDB).