Dedupe imported route modules in RSC Framework Mode

[markdalgleish]

As noted in the test in this PR, this ensures that code is not accidentally duplicated when a route is imported within user code since they're not importing one of our internal virtual route modules.

This is already the case in our existing Vite plugin, so I've also got the newly added test running against our standard Vite test template too.

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Latest commit: d575dd6

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[github-actions]

🤖 Hello there,

We just published version 7.8.2-pre.0 which includes this pull request. If you'd like to take it for a test run please try it out and let us know what you think!

Thanks!

[github-actions]

🤖 Hello there,

We just published version 7.8.2 which includes this pull request. If you'd like to take it for a test run please try it out and let us know what you think!

Thanks!