[chore] Make changing the name of a REPL obvious

[baseballyama]

Improvement of #6797

Honestly, I also took time to know I can edit a title of REPL.
So I tried to improve it according to the issue.

[Current Version]
https://svelte.dev/repl/hello-world?version=3.43.1

[After Improvement]
https://user-images.githubusercontent.com/19153718/135877687-d2f386dc-dd01-48ec-b69d-68bbafb05817.mp4

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Tests

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Thank you!

[Conduitry]

How about making the edit icon only appear when hovering over the name or when it has keyboard focus? I think it's a little distracting and unsightly to have that edit icon there at all times.

[baseballyama]

The propose of edit icon is that tell users that the title can be modified.
But if part of the users feel little distracting and unsightly,
I think we should remove edit icon because after hover / focus on title input, already users knows it can be edit.

This PR makes it easier for users to notice that the title can be edited, so from this point of view, it may be better to do without edit icon.

[tanhauhau]

Looks good to me

[benmccann]

I'm a bit confused. The video shows an icon, but I see only one file edited and it doesn't appear to be adding an icon. Is the video in the PR description outdated? What does this look like now?

[benmccann]

Ok, I see, this is just the hover. I think the size of the input on hover is a bit unsightly, but I'll go ahead and merge this since it's got a couple approvals because it's still an improvement and I don't want it to get lost in migrating things over to https://github.com/sveltejs/sites. It wouldn't be bad to add a max-width or something to the input in a follow up

[baseballyama]

OK!
I'll keep this in mind. And I will consider it after the migration is done.