Redesign @stlite/desktop's dump command API

[whitphx]

• Its options which we are now passing as command line args, e.g. the app directory and the requirements, should be defined in package.json.
  • Such file-based build config is more consistent and useful.
• Support an arbitrary entrypoint name.
• Support -p option like tsc to specify the project root dir where package.json exists. It's not fixed to process.cwd().

We should keep the current dump command marking it deprecated and create a new one for the compatibility.

[terapyon]

"e.g. the app directory" : Does this mean that we can use another app name for "streamlit_app"? If yes, it is very very useful. If no set for app name in package.json, to expect using streamlit_app.py.

[whitphx]

Thank you. Yes, I'm planning to allow any app name with such settings.