[Feature Request] Guide against single-file structure

Is your feature request related to a problem? Please describe.

Given this single-file pattern of running a Workflow inside a Worker:

https://github.com/temporalio/samples-python/blob/7b3944926c3743bc0dcb3b781d8cc64e0330bac4/hello/hello_activity.py#L47-L64

there is potential (and one past instance I know of) for people learning based off of samples to think that in order to run a Workflow, you need to run it inside an async with Worker. When they try to develop an application based on that paradigm, they run into a number of issues.

Describe the solution you'd like

Make it clear that when developing, we recommend:

• running a worker separately from workflows
• defaulting to a single worker for all workflows, not one worker per workflow

We could make it clear by structuring all samples that way. OTOH I like the brevity of the single file samples. Another possibility is changing the comment. The drawbacks to that are:

• some people don't read comments
• the comment might not be clear, unless you point to a multi-file sample, what exactly we recommend doing

Comment is currently:

# While the worker is running, use the client to run the workflow and
# print out its result. Note, in many production setups, the client
# would be in a completely separate process from the worker.

Perhaps could be:

# Use the client to run the workflow and print out its result. 
# NOTE: when developing, we recommend starting out running a 
# single worker that has all your workflow and activities and
# running client code in a separate process. See, for example,
# how the encryption sample has a separate files to run:
# worker.py runs the worker and starter.py uses the client.

从 hello/hello_activity.py 第 47-64 行开始，将其单文件 Worker 和 workflow 设置与加密示例中的 worker.py 和 starter.py 进行比较。确定指导内容应放在示例结构中还是注释中，然后更新相关示例，使独立的 Worker 和客户端进程，以及由一个 Worker 提供 workflows 服务的方式，都清晰且一致。