PR-733704: fix TypeScript errors in Cypress webpack build

Add tsconfig.cy.json that extends the main tsconfig but removes the
rootDir restriction and adds Cypress types. Point ts-loader in
webpack.cy.config.ts to this dedicated tsconfig, fixing:
- TS6059: cypress/support files outside rootDir src/components
- TS2307: missing @storybook/react-webpack5 type declarations
- TS2339: toBeInTheDocument not found (jest-dom types scope)

tsconfig.cy.json

@@ -0,0 +1,13 @@
+{
+	"extends": "./tsconfig.json",
+	"compilerOptions": {
+		"rootDir": ".",
+		"noEmit": true,
+		"types": ["cypress", "node"]
+	},
+	"include": [
+		"src",
+		"cypress",
+		"src/@types"
+	]
+}