Support X-Ray locally

According to the README:
> The component does _not_ support X-ray and other Lambda integrations locally.

So...how hard would it be to add this support for local X-Ray integration?

I think the primary use case for this would be to allow functions built with the SAM CLI that utilize X-Ray (e.g., with `AWSXRay.captureAWSv3Client`) to run locally. Not having this integration requires annoying hacks to import or not import the X-Ray SDK based on where the function is deployed. For more info, and to add some support to my request, please have a look at [this issue](https://github.com/aws/aws-sam-cli/issues/217) in the SAM CLI repo, where people have been ranting about this feature since 2017. 😅

Start with the README statement that local X-Ray and other Lambda integrations are unsupported, then read the linked SAM CLI issue #217 for prior context and requested behavior. Define the scope of local X-Ray integration and validate it against a SAM CLI function using AWSXRay.captureAWSv3Client; done means that function can run locally without conditional X-Ray SDK imports.

Written by the indexing model from the issue text.