staticwebapp.config.json -> routes redirect does not support fully qualified URLs

**Describe the bug**

Redirects with full URLs do not trigger redirects. Consider:

```json
{
"routes": [
{
"route": "https://blog.johnnyreilly.com/",
"redirect": "https://johnnyreilly.com/",
"statusCode": 301
}
],
}
```

This does not trigger a redirect from https://blog.johnnyreilly.com to https://johnnyreilly.com

https://github.com/johnnyreilly/blog.johnnyreilly.com/blob/3cd71d0b968b21ed82c8b248ef78993da2632783/blog-website/staticwebapp.config.json#L10-L14

Go to https://blog.johnnyreilly.com and you'll see it in action!

**Expected behavior**
A redirect

**Screenshots**

**Device info (if applicable):**
N/A

**Additional context**
https://github.com/johnnyreilly/blog.johnnyreilly.com/pull/477