feat(wasm): supporting cached dependencies

[Beanow]

Currently the WASM compiler only supports a root package without any dependencies.

The playground works around this by acting like the contents of gleam_stdlib are submodules of the package being compiled, rather than dependencies. This approach no longer works when you're trying to use more dependencies than one.

Suggested changes

• Add support for loading the /lib path in a similar way to the gleam-cli compiler.
• Add optional support for loading a gleam.toml config.

This would be a backwards-compatible incremental feature. And because this would reduce the "drift" between gleam-cli and gleam-wasm should not introduce any controversial quirks specific to the WASM version.

Alternative

One could also attempt to "build project" with the WASM compiler.
So rather than loading modules from build cache, compiling dependencies from a package source.

This is a larger effort though and seems more in scope for a breaking change to the WASM compiler.
Besides, you'd still want to support build caching and need to support loading the config file in that case.

[lpil]

Are you having performance problems running the compiler without caching? How long is it taking to run for you?