refactor(cli): decouple bundler from cargo

[lucasfernog]

What kind of change does this PR introduce? (check at least one)

• Bugfix
• Feature
• New Binding Issue #___
• Code style update
• Refactor
• Build-related changes
• Other, please describe:

Does this PR introduce a breaking change? (check one)

• Yes. Issue #___
• No

The PR fulfills these requirements:

• When resolving a specific issue, it's referenced in the PR's title (e.g. fix: #xxx[,#xxx], where "xxx" is the issue number)
• A change file is added if any packages will require a version bump due to this PR per the instructions in the readme.

If adding a new feature, the PR's description includes:

• A convincing reason for adding this feature (to avoid wasting your time, it's best to open a suggestion issue first and wait for approval before working on it)

Other information:

This is a step towards the CLI being used to compile other projects (e.g. Deno in the future). The bundler doesn't do Cargo specifics anymore, and the previous functionality was moved to the core CLI, in a rust mod containing the implementation for Rust packages. The idea is to extend that to other languages in the future.

[nklayman]

Worked great for me on linux, nice job!

[lucasfernog]

Seems like my commit signing isn't working properly on my laptop, i'll fix it for next time.