Add regex capabilities to redirects

## Prerequisites

* [x] I am running the latest version. (`up upgrade`)
* [x] I searched to see if the issue already exists.
* [x] I inspected the verbose debug output with the `-v, --verbose` flag.
* [ ] Are you an Up Pro subscriber?

## Description
It would be great to add regex capabilities to redirects like so:
```
redirects: {
"/folder/:slug(regexhere)": {
"location": "https://.../:slug",
"status": 301
}
}
```