fix: code snippet layout

[pauldambra]

I was trying to use code snippet actions for https://github.com/PostHog/posthog/pull/22111 and noticed that the copy button looked offset in most cases

So, I've tweaked its position a little

Also adds some more examples of usage to the StoryBook that would have more quickly let me see I couldn't use this component in #22111

(I'm expecting snapshot tests to show what I've changed :))

[posthog-bot]

📸 UI snapshots have been updated

48 snapshot changes in total. 0 added, 48 modified, 0 deleted:

• chromium: 0 added, 48 modified, 0 deleted (diff for shard 1, diff for shard 2)
• webkit: 0 added, 0 modified, 0 deleted

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👉 Review this PR's diff of snapshots.

[github-actions[bot]]

Size Change: 0 B

Total Size: 1.05 MB

ℹ️ View Unchanged

Filename	Size
frontend/dist/toolbar.js	1.05 MB

_{compressed-size-action}

[posthog-bot]

📸 UI snapshots have been updated

60 snapshot changes in total. 0 added, 60 modified, 0 deleted:

• chromium: 0 added, 60 modified, 0 deleted (diff for shard 1, diff for shard 2)
• webkit: 0 added, 0 modified, 0 deleted

Triggered by this commit.

👉 Review this PR's diff of snapshots.