Use NODEJS_20_X

### Use Case

Lambda NODEJS_14_X runtime is used at multiple places https://github.com/search?q=repo%3Aaws-samples%2Faws-sam-support-aws-cdk%20NODEJS_14_X&type=code

It's function create is blocked as of `Jan 9, 2024`.
Lambda Supported Runtimes https://docs.aws.amazon.com/lambda/latest/dg/lambda-runtimes.html

### Proposed Solution

Use NODEJS_20_X, which [was made available on Nov 15, 2023](https://aws.amazon.com/blogs/compute/node-js-20-x-runtime-now-available-in-aws-lambda/)

Start with the repository code search for NODEJS_14_X and inspect each matching runtime definition or function creation path. Replace the blocked runtime references with NODEJS_20_X, then verify that every listed occurrence has been updated and that the affected functions can still be created.

Written by the indexing model from the issue text.