JS/Python package names improvements about wasmer-pack

[Michael-F-Bryan]

@syrusakbary, I just played around with this and I'm not sure if I like the way packages get named.

For example, wasmer/wasmer-pack is turned into wasmer_package__wasmer__wasmer_pack on Python and @wasmer-package/wasmer__wasmer-pack on JavaScript. Compare that with wasmer_pack and @wasmer/wasmer-pack under the existing naming scheme.

I know package names are just labels, but they feel kinda clunky and could be a pain for end users to import every time.

Instead of publishing to PyPI and NPM, what if we hosted our own alternate registries? Pip, NPM, and Cargo all support the concept of alternate registries, and that way we wouldn't need to worry about namespacing.

I guess it's a trade off, though. Hosting our own registry gives us lots of flexibility, but most registries require you to only have dependencies from the same registry, so it means people can't use WAPM packages if they want to publish to PyPI/NPM/Crates.io 😞

[syrusakbary]

This can be solved easily by a new --package-name flag provided to the wasmer-pack cli.

Where the user of the CLI actually decides what's the package name.
Wasmer pack can choose the default and users can override it.

This also helps if in the future we don't include the package name metadata in the webc