refactor: move SqlFormatter from direct import to DeparserContext property

- Add SqlFormatter as a property of DeparserContext with default instantiation
- Replace all this.formatter references with context.formatter throughout deparser
- Remove direct SqlFormatter import and private formatter property from Deparser class
- Update deparse() and visit() methods to create context with formatter when not provided
- Maintain modular design allowing external formatter instantiation and context passing
- Preserve existing formatting logic while improving context-aware formatting
- All 279 test suites continue to pass

Co-Authored-By: Dan Lynch <[email protected]>

Author: pyramation