Ruby analysis support for CodeQL

Under development.

Building the tools from source

Install Rust, then run:

cargo build --release

Generating the database schema and QL library

The generated ruby.dbscheme and ruby_ast.qll files are included in the repository, but they can be re-generated as follows:

# Run the generator
cargo run --release -p ruby-generator
# Then auto-format the QL library
codeql query format -i ruby_ast.qll