support cross builds and npm publish

[OmarTawfik]

In this PR

• add support for publishing npm packages for slang.
• add ability to cross-build native NAPI modules for 9 targets.
• replace Hermit's rust package with rustup to allow installing multiple targets.
• now CI will check to make sure TypeScript sources are up to date and pass tests on every push.
• fill NPM packages metadata, including platform-specific ones.
• removed yarn since it is no longer needed. standardizing on npm everywhere.
• following publishing, moved directory structure to solidity/outputs/cargo and solidity/outputs/npm, and within each, three sub-folders: build, crate, and tests. That separation makes sure our internal codegen crates are not propagated to product crates.

Changes to dev scripts

So far we have relied on cargo workspace commands (scripts/cargo/check.sh and scripts/cargo/test.sh). Each crate uses its own build.rs to define specific build steps that need to happen.

With this PR, adding NPM publishing, we do the same with the root package.json. Each package will define custom tasks in its own package.json, and we will run all of them through scripts/npm/build.sh and scripts/npm/test.sh.

For example, the NAPI packages in crates/solidity/outputs/npm will call NAPI specific scripts defined in scripts/npm/napi to build/test/publish.

Limitations

• Actual publishing is still disabled in CI. Once we figure out final package names, will update the source and re-enable it.
• enable cross-platform testing for NAPI native modules #410 as NPM testing is only local for now (linux on devcontainer).