…5027)

If we have `routes/path-a/+page.svelte`

The function `resolve()` propose us two options today
```ts
resolve('/path-a')
resolve('/path-a/')
```

As trailing slash default is `never`, I would expect that
`resolve('/path-a/')` is not available.
If you set `always`, I would expect only `resolve('/path-a/')` to be
available.

This PR is addressing this.
But... not that happy that:
- [x] I have to `read` in
`packages/kit/src/core/sync/create_manifest_data/index.js`
- [x] didn't manage to use
https://github.com/jycouet/kit/blob/7acee7aef9ac80614f9a78635cdf4a2a23785961/packages/kit/src/exports/vite/static_analysis/index.js#L213
as it's async

I added a few unit tests to help playing around.
Any help on the stuff I'm not happy about ?

---

### Please don't delete this checklist! Before submitting the PR, please
make sure you do the following:
- [ ] It's really useful if your PR references an issue where it is
discussed ahead of time. In many cases, features are absent for a
reason. For large changes, please create an RFC:
https://github.com/sveltejs/rfcs
- [x] This message body should clearly illustrate what problems it
solves.
- [x] Ideally, include a test that fails without this PR but passes with
it.

### Tests
- [x] Run the tests with `pnpm test` and lint the project with `pnpm
lint` and `pnpm check`

### Changesets
- [x] If your PR makes a change that should be noted in one or more
packages' changelogs, generate a changeset by running `pnpm changeset`
and following the prompts. Changesets that add features should be
`minor` and those that fix bugs should be `patch`. Please prefix
changeset messages with `feat:`, `fix:`, or `chore:`.

### Edits

- [x] Please ensure that 'Allow edits from maintainers' is checked. PRs
without this option may be closed.

---------

Co-authored-by: Tee Ming <chewteeming01@gmail.com>