expandGlob: support an ignore permission denied option

**Is your feature request related to a problem? Please describe.**

Currently if you encounter an error due to os permission, if make the whole walk stop.
```
error: Uncaught (in promise) PermissionDenied: Permission denied (os error 13): readdir '/snap/core20/2379/etc/ssl/private'
for await (const entry of Deno.readDir(root)) {
```
An option to "skip" permission denied files would be nice

**Describe the solution you'd like**

A new option

**Describe alternatives you've considered**