Support more languages and package managers in the VM

[ishaan1013]

Current VM setup supports basic Node.js/npm environments

• Add support for Python (pip), Rust (cargo), Go (go mod), Java (maven/gradle)
• Update sidecar CommandService to handle language-specific package managers
• Enhance VM initialization to detect and configure appropriate language environments

[zudsniper]

could just allow users to plug in their own setup, a la cursor background agents, and then also allow them to "publish" them to the "marketplace", a la devcontainers' way of handling features (like docker-in-docker). it seems like that would be the best long term, but it would be more work up front