Allow to change port from default 8501

[bobbypage]

It doesn't seem like preswald currently supports running on ports other than 8501.

As an example:

$ git clone https://github.com/StructuredLabs/preswald.git
$ cd /preswald/examples/network

$ preswald run hello.py --port 8000
Running 'hello.py' on http://localhost:8000 with log level INFO  🎉!
Starting Preswald server at http://localhost:8000
Using port 8501 from config.toml
Will run script: /preswald/examples/network/hello.py
INFO:     Started server process [487]
INFO:     Waiting for application startup.
INFO:     Application startup complete.
INFO:     Uvicorn running on http://0.0.0.0:8501 (Press CTRL+C to quit)

I saw the message Using port 8501 from config.toml, so I assumed the the port is coming from the config. I adjusted the config:

root@40247a2e968d:/preswald/examples/network# cat config.toml
[project]
title = "Network Topology | Preswald"
version = "0.1.0"
port = 8000 <---

and trying again:

root@40247a2e968d:/preswald/examples/network# preswald run hello.py --port 8000
Running 'hello.py' on http://localhost:8000 with log level INFO  🎉!
Starting Preswald server at http://localhost:8000
Using port 8000 from config.toml
Will run script: /preswald/examples/network/hello.py
INFO:     Started server process [496]
INFO:     Waiting for application startup.
INFO:     Application startup complete.
INFO:     Uvicorn running on http://0.0.0.0:8501 (Press CTRL+C to quit)

We see

Using port 8000 from config.toml

However, still seems like the port used by the server is 8501.

I would expect that the preference of the port would be:

1. From the --port flag (if supplied)
2. From the config.toml (if supplied)
3. Default to some well known port like 8501

[amrutha97]

Thanks! taking a look