Introduce ParseServeOptions as public API

[osdevisnot]

with sorvor, I use ParseBuildOptions as it helps me reuse same argument parsing logic as esbuild cli itself. This is beneficial for end users since they can then swap sorvor with esbuild without changing the cli arguments if sorvor does not meet their expectations.

However, the argument parsing for serve mode, specifically --serve=8000 or --servedir= are not exposed through a public API.

Would you consider adding a new ParseServeOptions as a public API?

I imagine the usage would then be something like this:

var serveOptions = api.ParseServeOptions(osArgs...)