Patch for Github issue #524

[neelkanth-kaushik]

This PR patches the Github issue #524

This pull request improves the shutdown process for the AnalyticsClient by ensuring that all messages are properly processed before shutting down executors. The changes address a potential race condition during shutdown and add better error handling for task submission failures.

Shutdown process improvements:

• Introduced a Future<?> looperFuture to track the completion of the Looper thread, allowing the shutdown process to wait for the looper to finish processing all messages before shutting down executors. This prevents a race condition where the network executor could be shut down before all batches are submitted.
• Added a waitForLooperCompletion() method that waits (with timeout) for the looper to finish, logs completion or errors, and cancels the looper if it takes too long.

Error handling enhancements:

• Wrapped network batch submission in a try-catch block to handle RejectedExecutionException during shutdown, logging the error and notifying callbacks of the failure if the batch cannot be submitted.

Dependency updates:

• Added imports for Future and RejectedExecutionException to support the new shutdown and error handling logic.