type-sitter-lib: type-sitter code for generated / downstream code

See type-sitter for more information. This is the library code generated from type-sitter depends on. It also contains the tree-sitter-wrapper feature, which provides a lightweight general-purpose wrapper over tree-sitter nodes: these wrappers have convenience functions like getting a node's text as a &str and assigning arbitrary bitmasks ("marks") to each node, at the cost of slightly lower performance.