feat(xychart): add per-point text labels for line charts#7550

DominicBurkart wants to merge 4 commits intomermaid-js:developmermaid-js/mermaid:developfrom

DominicBurkart:feature/7549_xychart-point-labelsDominicBurkart/mermaid:feature/7549_xychart-point-labelsCopy head branch name to clipboard