Grafana-UI: add storysource addon to Storybook (#22490)

* Add @storybook/addon-storysource

* Enable the addon

* Fix Select label

* Lock storysource version

packages/grafana-ui/.storybook/main.ts

@@ -5,5 +5,6 @@ module.exports = {
     '@storybook/addon-actions',
     '@storybook/addon-docs',
     'storybook-dark-mode/register',
+    '@storybook/addon-storysource',
   ],
 };

packages/grafana-ui/package.json

@@ -69,6 +69,7 @@
     "@storybook/addon-docs": "5.3.9",
     "@storybook/addon-info": "5.3.9",
     "@storybook/addon-knobs": "5.3.9",
+    "@storybook/addon-storysource": "5.3.14",
     "@storybook/react": "5.3.9",
     "@storybook/theming": "5.3.9",
     "@types/classnames": "2.2.7",

packages/grafana-ui/src/components/Forms/Form.story.tsx

@@ -98,7 +98,7 @@ const renderForm = (defaultValues?: Partial<FormDTO>) => (
             <Forms.InputControl name="radio" control={control} options={selectOptions} as={RadioButtonGroup} />
           </Field>
 
-          <Field label="RadioButton" invalid={!!errors.select}>
+          <Field label="Select" invalid={!!errors.select}>
             <Forms.InputControl
               name="select"
               control={control}