Install Storybook

Installed Storybook with webpack5 as builder. Also added `eslint-plugin`
and did the `npm7` migration (generating the `.npmrc`-file), as
recommended by the storybook installer.

Deleted the contents of `src/stories`, meaning that Storybook has no
stories it can display. The server starts up though.

.npmrc

@@ -0,0 +1 @@
+legacy-peer-deps=true

.storybook/main.js

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+module.exports = {
+  "stories": [
+    "../src/**/*.stories.mdx",
+    "../src/**/*.stories.@(js|jsx|ts|tsx)"
+  ],
+  "addons": [
+    "@storybook/addon-links",
+    "@storybook/addon-essentials",
+    "@storybook/addon-interactions"
+  ],
+  "framework": "@storybook/react",
+  "core": {
+    "builder": "@storybook/builder-webpack5"
+  }
+}

.storybook/preview.js

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+export const parameters = {
+  actions: { argTypesRegex: "^on[A-Z].*" },
+  controls: {
+    matchers: {
+      color: /(background|color)$/i,
+      date: /Date$/,
+    },
+  },
+}