Move rescope token request to IO thread

[CDRussell]

Task/Issue URL: https://app.asana.com/1/137249556945/project/608920331025315/task/1213530835574684?focus=true

Description

Moves the network request that happens in GetScopedSyncAuthTokenHandler to an io thread instead of trying to do it on the java bridge thread (which is for JS->Native comms).

Steps to test this PR

• QA optional

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Note

Medium Risk
Moves token rescoping into an injected app-level coroutine on the IO dispatcher, introducing async behavior that could affect response timing/cancellation and test determinism if dispatchers/scopes are misconfigured.

Overview
GetScopedSyncAuthTokenHandler now performs syncApi.rescopeToken asynchronously by launching on an injected @AppCoroutineScope with dispatcherProvider.io(), instead of executing inline on the message handler thread.

Tests are updated to inject a CoroutineTestRule test scope/dispatcher provider so the new coroutine-based behavior remains verifiable while keeping the existing success/error response and pixel assertions intact.

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[CDRussell]

• Move rescope token request to IO thread #7869 👈 (View in Graphite)
• develop

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[joshliebe]

LGTM 🙂