Implement ui.navigate functionality

[ZeroCool940711]

This PR adds the ui.navigate module, which includes the ui.navigate.back(), ui.navigate.forward(), and ui.navigate.to() methods. These methods allow for programmatic navigation within the browser history and redirecting to specific URLs or page functions.

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Feature request: #2575

[rodja]

Maybe we should implement it inside a class instead of free functions. That would allow replacing/updating the implementation for single page applications (SPAs) for example.

[falkoschindler]

@rodja Is this what you had in mind?

I'm quite happy with the current implementation. I also deprecated ui.open, although I'm not sure if we really want to print a warning or if we should simply keep ui.open as a valid alias for now.

[rodja]

@falkoschindler I think it's better to not print warnings when using ui.open because it will pollute the logs quite a bit.

I've meddled a bit with the documentation structure and internals to make sure https://nicegui.io/documentation/open is not showing a 404.

[rodja]

From my side it's ready to merge.