Relative References + Autocomplete Formulas

[luke-quadratic]

Autocomplete fills in formulas with relative references. Copy/paste should also paste relative cell references in formulas, not absolute references.

Tasks

• [x] Auto-complete code cells (formulas and python): https://github.com/quadratichq/quadratic/pull/1230
• [ ] Relative references in auto-complete
• [ ] Relative references in copy/paste