[Bug] The sample index file doesn't know about subdirectories

Some of our samples are grouped in subdirectories, e.g. message-passing/execute-update. However, the script that refreshes the list-of-samples.json file doesn't know about that structure, do the index file only contains the parent directory, e.g. message-passing.

Note that there might also be a related issue with the @temporalio/create command in instantiating a local repo from such a sample.

Repro

samples-typescript(pnpm) npx @temporalio/create@latest my-project
[...]
✔ Which sample would you like to use? › message-passing
Could not locate a sample named "message-passing". It could be due to the following:
 1. Your spelling of sample "message-passing" might be incorrect.
 2. You might not be connected to the internet.

Available samples:

[...]
message-passing
[...]

Start by tracing the script that generates list-of-samples.json and the @temporalio/create sample-selection path, using the message-passing/execute-update example as the case to follow. Check how nested sample directories are indexed and instantiated. Done means the index exposes the usable nested sample and npx @temporalio/create can select and create a project from it.