Link get started last step to the site dashboard where possible

[morekid]

We should investigate a way to link back to the site dashboard in the app on the last step of Get started guides (eg: https://docs.arcjet.com/get-started?f=sveltekit#4-start-app).

We currently link generically to the app which is not ideal.

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If customers have followed the guide or are coming from the app onboarding they will already have an open tab pointing to the site they just created so we might just need to focus that tab.