Avoid trailing slashes on urls that look like files. The redirect for `trailingSlash: true` will now look like:

```
Redirects

┌ source: /:path*/:file.:ext/
├ destination: /:path*/:file.:ext
└ permanent: true

┌ source: /:path*/:notfile([^/.]+)
├ destination: /:path*/:notfile/
└ permanent: true
```

The default still looks like:

```
Redirects

┌ source: /:path+/
├ destination: /:path+
└ permanent: true
```
After this gets merged, I have a few optimizations planned on the normalization code that should reduce the client bundle a little and that consolidates the `trailingSlash` and `exportTrailingSlash` options