There are two parts to this commit:
1. Revert the changes from #38379. This change had an incomplete view of
how things worked and also diverged the implementations of
`applyRedirects` and `recognize` even more.
2. Apply the fixes from the `recognize` algorithm to ensure that named
outlets with empty path parents can be matched. This change also passes
all the tests that were added in #38379 with the added benefit of being
a more complete fix that stays in-line with the `recognize` algorithm.
This was made possible by using the same approach for `split` by
always creating segments for empty path matches (previously, this was
only done in `applyRedirects` if there was a `redirectTo` value). At the
end of the expansions, we need to squash all empty segments so that
serializing the final `UrlTree` returns the same result as before.
Fixes#39952Fixes#10726Closes#30410
PR Close#40029
e43f7e26fe