Need next route for unstable_useBlocker and unstable_usePrompt

[resatDev]

After the Prompt component was removed, the unstable_useBlocker and unstable_usePrompt hooks were added again. However, the "message" prop, which is one of the most important features of the Prompt component, does not have the ability to work as a function. One of the parameters that the function message prop return was the next route to proceed. I will need this as soon as possible. The nextPathname prop used in the unstable_useBlocker hooks is the related prop which I need.

[brophdawg11]

The primary way to block navigation in RouterProvider is unstable_useBlocker, which gives you control over the UI and avoids messy edge cases that come with usePrompt (since browsers handle back/forward navigations while the confirm dialog is open quite differently). We do not have plans to enhance unstable_usePrompt at this time - it's only about 20 lines of code wrapping unstable_useBlocker so your best path forward at this time would be to copy it and modify it to suit your needs - specifically by passing a function to useBlocker instead of a boolean.