Add adding existing node.js APIs to Javascript examples

[indcoder]

Describe the issue or suggestion

In the JavaScript/Node articles, the examples are exclusively on frontend frameworks, but is missing on how to add existing/brownfield node.js APIs

1. Other than frontend frameworks as JavaScript examples, we need to add examples on reusing their existing Node.js API as part of the Aspire Application model
2. A primer on the instumentation.js that needs to be added to the JS projects so that they are Aspire compatible.
3. Guidance on where the configuration values/secrets need to be stored: at the node.js level or part of the AppHost app settings?

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Associated WorkItem - 308085

[indcoder]

Also,

1. We need to be nuanced and provide more use cases when to use AddNPM and AddNode. Right now, its too terse.

2. Also , it not mentioned anywhere in the doc that you need to add Aspire.Hosting.NodeJs, hence you dont get the two above function in the builder

Only when you peruse the github sample and inspect the AppHost and see in its dependency that you missing to add the nuget