[ENH] Running list of minor improvements

[ankurankan]

• The unwrap_or used at: https://github.com/pgmpy/causalgraphs/blob/main/wasm_bindings/src/lib.rs#L23 should be moved to the core Rust if possible. This should be the common default value for all bindings and core package.
• derive(Clone) used here should be moved to the core package if possible.
• Move all the generated packages to a single directory for easy maintenance. Currently, the files from the rust package are generated in target, from wasm in js/pkg-node, etc.
• Remove the test.py file: https://github.com/pgmpy/causalgraphs/blob/main/python_bindings/test.py