fix: dispatch handlers via live lookup instead of .bind() snapshot

[bro-ankit]

Summary

Fixes #108 — SqsService binds @SqsMessageHandler/@SqsConsumerEventHandler methods via .bind() at onModuleInit, capturing a frozen snapshot of the method at that exact moment. Any provider that wraps a decorated method after that point — a standard Nest extension pattern (see @golevelup/nestjs-discovery's own docs, which cite @nestjs/graphql's @Mutation/@Resolver discovery as the reference example) — has that wrapping silently ignored for SQS-bound handlers. The message still processes (nothing crashes), but any cross-cutting logic layered on top never fires. No error, no warning.

This isn't a contrived timing edge case: onModuleInit runs strictly before onApplicationBootstrap for the entire application, across every module, regardless of import order. Any executor using OnApplicationBootstrap (a common choice, since it's guaranteed to run after all onModuleInit hooks) hits this on every SQS handler, unconditionally.

Fix

Replaced the .bind() capture (handleMessage, handleMessageBatch, event listener) with a closure that looks up instance[methodName] at call time:

// before
handleMessage: metadata.discoveredMethod.handler.bind(metadata.discoveredMethod.parentClass.instance)

// after
handleMessage: (...args) => instance[methodName](...args)

[bro-ankit]

@ssut could you take a look when you get a chance?

[bro-ankit]

@ssut Hi! Just a friendly follow-up on this PR. I can work around it with a local patch, but I'd prefer to get this upstream instead. I'd appreciate a review when you have a chance. Thanks!