Implement CodeGen

[alexdovzhanyn]

As per analysis done in #3 , we'll be targeting WASM as the backend for the Theta language.

• [x] Implement a codegen step to convert Theta AST to WebAssembly binary format, using binaryen
• [x] Test the WebAssembly output to ensure correct and efficient execution.
  • [x] Write and run test cases to validate the generated WebAssembly code.
  • [x] Optimize the codegen process for performance and size efficiency.