[storybook] Cleans data.json

Details:
- Moves data.json from public to stories/_data (new folder)
- Removes other local data.json that were in some stories, and replaced
  them by stories/_data/data.json

packages/storybook/stories/events/index.ts

@@ -5,8 +5,8 @@ import Graph from "graphology";
 import Sigma from "sigma";
 import { MouseCoords } from "sigma/types";
 
+import data from "../_data/data.json";
 import { onStoryDown } from "../utils";
-import data from "./data.json";
 
 export default () => {
   const container = document.getElementById("sigma-container") as HTMLElement;

packages/storybook/stories/layer-webgl/contour-line.ts

@@ -4,7 +4,7 @@ import louvain from "graphology-communities-louvain";
 import iwanthue from "iwanthue";
 import Sigma from "sigma";
 
-import data from "../../public/data.json";
+import data from "../_data/data.json";
 import { onStoryDown } from "../utils";
 
 export default () => {

packages/storybook/stories/layer-webgl/plain-contour-lines.ts

@@ -2,7 +2,7 @@ import { bindWebGLLayer, createMetaballsProgram } from "@sigma/layer-webgl";
 import Graph from "graphology";
 import Sigma from "sigma";
 
-import data from "../../public/data.json";
+import data from "../_data/data.json";
 import { onStoryDown } from "../utils";
 
 export default () => {