Unable to instrument files that are not an npm package

[bizob2828]

Description

Prior to v11.0.0 of the agent, you could use the API instrument, instrumentMessages, etc to instrument any file. The moduleName had to be the first time the package is required. In v11.0.0 we switched to use require-in-the-middle to instrument CommonJS modules.

In the v11.0.0 changelog we did call out: "You can no longer instrument files that are not within a node_module unless you provide an absolute path to the file when registering the instrumentation." However, that's not entirely possible.

Expected Behavior

Provide ability to instrument a file that's not within a 3rd party package.

You should see this in the output of repro app

[NEWRELIC] instrumenting nifty-messages
[NEWRELIC] instrumenting method 'publish'
[NEWRELIC] instrumenting method 'purge'
[NEWRELIC] instrumenting callbacks of method 'getMessage'
[NEWRELIC] instrumenting callbacks of method 'subscribe'

Steps to Reproduce

1. Clone this repo
2. Follow readme but upgrade to latest agent npm i newrelic@latest
3. Run npm start

Additional context

This probably doesn't affect any customers. It just makes it easier for us to show how to use the instrument API methods by building some contrived "module" but have it live within the application.

[workato-integration]

https://new-relic.atlassian.net/browse/NR-218827