fs/walk do not include folders if exts option is given

**Describe the bug**

Using `fs/walk` or `fs/walkSync`, if `exts` options is given, and `includeDirs: true` (default), the folders name are tested against `exts` extensions what is a non-sense and will most of time exclude the folder (cause 🤷🏻‍♂️ they don't have extension).

**Steps to Reproduce**

```js
walk(path, {
includeDirs: true,
exts: ['js','es','ts']
})
```

**Expected behavior**

When including folders, their name have to be tested against `match` or `skip` but not `exts`

**Environment**

- OS: linux mint
- deno version: 1 & 2
- std version: jsr:@std/fs/1.0.18/walk.ts