type-sitter-gen: base functionality to generate typed wrapper nodes for type-sitter

See type-sitter for background information. This library allows you to generate type-sitter wrappers with more flexibility than type-sitter-cli and type-sitter-proc. It's the only way (outside of manually editing code generated by type-sitter-cli) to generate wrappers which import something that isn't tree_sitter, generate queries without some of their patterns and captures, or combine multiple generations into one file.