"no exported member 'mockLogger'" error when mocking the library in TypeScript

## Context

I'm using this library to send metrics via the `metricScope` and I need to test the functionality. To do so I'm following the example described here https://github.com/awslabs/aws-embedded-metrics-node/blob/master/examples/testing/tests/module.jest.test.js.

The project is written in TypeScript and I use jest for unit testing.

## Issue

This example https://github.com/awslabs/aws-embedded-metrics-node/blob/master/examples/testing/tests/module.jest.test.js fails in a TypeScript context with the following error:

```
Module '"aws-embedded-metrics"' has no exported member 'mockLogger'.ts(2305)
```

## Question

* How do I expose the `mockLogger` to the test function without making TypeScript complain?
* Is there a different approach to mock the logger and expose it to the test?

Start with examples/testing/tests/module.jest.test.js and reproduce the TypeScript error that mockLogger is not exported. Then inspect the library's TypeScript exports and declarations to determine how the testing logger is exposed. Done means the example can access mockLogger without a TypeScript export error, or the supported alternative is documented.

Written by the indexing model from the issue text.