[Lambda] Layer: Show code source in Lambda Code Source Explorer

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**Tell us about your request**
Enable the Lambda code source explorer to display the code source of layer(s) associated with the function. The code could be read-only but would allow developers to view function definitions and documentation directly within the Lambda console.

**Which service(s) is this request for?**
AWS Lambda

**Tell us about the problem you're trying to solve. What are you trying to do, and why is it hard?**
Currently, when using Lambda layers, there is no direct way to view the source code of functions provided by the layer within the Lambda console. Developers must download .zip file of the layer's source code and read it externaly, which disrupts the workflow and makes debugging or hot fix harder.

**Additional context**
This feature would improve developer productivity by providing better visibility into layer contents.

**Attachments**
N/A