generate deterministic IDs for SVG elements to facilitate diff

When saving figure as SVG using write_image, Plotly Express generates random unique IDs for elements. As a result, git diff thinks re-generated figures have changed even when they haven't (see screenshot). If the IDs were generated in some deterministic way depending solely on figure contents, so that they only changed when the figure itself had visually changed, git would be a lot happier.

see #3393

SVG出力のwrite_imageエントリポイントから始め、issue #3393の関連する議論を確認してください。要素IDが現在どのように生成されているかを特定し、図の内容のみに基づく決定論的な方式を定義してください。変更されていない図を再生成したときに安定したSVG IDが生成され、git diffが視覚的な変更のみを反映すれば完了です。