Domain-specific configurations

**Describe the idea / solution you'd like**
it'd be nice to be able to have domain-specific configs, like you can have certain shares valid for one domain and other shares valid for another.

as an example, say i have `sub1.example.com` and `sub2.example.com` and i want `sub1` to only have access to the `sub1` share, something like:
```
[domain sub1.example.com]
[/sub1]
/srv/http/sub1

[domain sub2.example.com]
[/sub2]
/srv/http/sub2
```

afaik this isn't a thing you can do. i've messed around with rewrites and got something mostly functional but it's still very janky (random 404s) and requires much, much domain-specific config and only can work with one share per domain