Print/stdout statement for debugging

It would be helpful to me in getting up to speed on bicep and debugging if there were a print or stdout statement, like [this request on stackoverflow](https://stackoverflow.com/questions/67936416/how-to-write-a-variable-parameter-to-stdout). In one areas I wanted to see if a managed identity exists and print the id if it did. That's pretty simple and may not seem like a necessity but as I get into loops it would help to see what I'm getting back and if I need any additional formatting (e.g. does the output I get match the input formatting I need for the next call).

A simple example might be using "existing" to get a managed identity and seeing if it actually worked.

**Describe the solution you'd like**
Simply print the output to the console when I'm running it in VS Code and I expect when it's in GitHub Actions that it would do the same.

Start by reviewing how Bicep execution and deployment output are surfaced in VS Code and GitHub Actions. Define the supported print or stdout behavior, including how values from existing resources and loops would appear, and document the expected result in both environments.

Written by the indexing model from the issue text.