Add example of a file editor toolbar button to the toolbar examples

[ktaletsk]

Implements #188

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This will close #188

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[ktaletsk]

For some reason, I can't get Github to correctly match index.ts in the old and new location

[fcollonval]

For some reason, I can't get Github to correctly match index.ts in the old and new location

The amount of changes is too high for git to consider it as a rename.

Would you mind fixing the CI (in particular the linter)?