Add Dockerfile, allow external dependencies and run rust tests

[douglasiacovelli]

Proposal

This allows running SandboxFusion with a Dockerfile that extends its functionalities to ensure new external dependencies can be easily added and also allowing to run tests for Rust instead of a main function.

Dependencies supported

All dependency files are expected to contain one dependency per line.

- Java: dependencies must be added in the java-dependencies.txt with each line being a maven JAR URL
- Ruby: dependencies must be added in the ruby-dependencies.txt file
- Python: dependencies must be added in the python-dependencies.txt file
- Node.js: dependencies must be added in the node-dependencies.txt file

Caveats

• The current implementation breaks the Rust execution when it relies on a main function. Ideally this should be done as a separate "language", such as Rust Tests
• The current Dockerfile is focused on reducing build time, therefore it applies the changes to the source code during build time by replacing the sandbox/runners/major.py