### What?
This modifies the static generation store to instead store a `url`
object with the `pathname` and `search` properties. This corrects the
previous behaviour which used the variable `urlPathname` which had
ambiguous meanings as it technically contained the search string as
well, not just the pathname.
In cases during the app render, this still grabs the contents of
`url.pathname + url.search` (where `url.search` always has a leading `?`
if it has any query parameters, [see the
docs](https://developer.mozilla.org/en-US/docs/Web/API/URL/search)) so
that it emulates the current behaviour. This allows more specific access
though, where now additional parsing can be eliminated which had to
strip the query string off of the `urlPathname` in a few places, and
more worrisome, still accidentally contained the search string causing
errors.
### How?
This requires an upstream fix (#64088) which corrected a bug with the
store access which had caused some previous test failures (accessing
`store.url.pathname` was throwing as `store.url` was undefined on the
wrong return, check the upstream PR for more details on that).
This also changes out usage of `pagePath` with `route`, and lets it be
the fallback (for debugging and error messaging). During static
generation, we will provide a value for the page being rendered that's
correlated to the particular file on the filesystem that the route is
based on:
```
// rendering app/users/[userID]/page.tsx
page: /users/[userID]
pathname: /users/1, /users/2, etc
```
The `route` is used only for debugging, such as when
`generateStaticParams` incorrectly calls `headers()`.
This also moves the pathname from the `staticGenerationStore` into the
`requestStore`, as it's tied to a given request.
Closes NEXT-2965
f0e4298f67