modules: optional: Feature update for Rust

Move to the latest Rust.

This moves the rust support to the latest version of the module:

    commit 49c6712fe53b5b82e5c09e94548a4a51a021acfe
    Author: David Brown <david.brown@linaro.org>
    Date:   Wed Feb 12 12:16:22 2025 -0700

        zephyr: various comment cleanups from review suggestions

This primarily brings in support for Zephyr Work queues, along with an
implementation of an Async Executor built using work queues and triggered
work to schedule the execution.

Signed-off-by: David Brown <david.brown@linaro.org>