Implement Storybook Code tab for stories

[larsrickert]

Why?

In #1898 we removed all examples except the default one from the docs page to address performance issues.
This now has the downside that the Vue code for the remaining examples can not be shown/copied by the users.

To fix this, we want to contribute to Storybook by implementing a new "Code" panel when viewing a single story which shows the current code snippet with copy functionality. There is also an existing discussion in the Storybook repository which appreciates this new feature: storybookjs/storybook#26691

We already contributed a lot to Storybook to improve the code snippet generation itself (see Storybook PRs) so not being able to view/copy the code snippets would be a big bummer.

Design

Acceptance criteria

• Single Storybook stories show a new "Code" panel which shows the current code snippet
• the code snippet can be copied to the clipboard

Definition of Done

• follow-up tickets were created if necessary
  • Update Storybook dependencies to include "Code" panel for stories #1963

Approval

• Storybook PR
• approved by Storybook maintainer chakAs3

Implementation details

• Should be implement inside the official Storybook docs addon
• Storybook panels docs
• Source code generation reference

[larsrickert]

storybookjs/storybook#29253