Allow hostname in Add-Server dialog

[bb]

Currently there's a validation that an IP is entered in the add-server dialog. In addition, it would be nice if a hostname could be added.

As a further enhancement (maybe worth a separate ticket), I have some Meili instances mounted in a subfolder, e.g. https://example.org/meili/ and I'd like to use this address directly. As you can see, this would combine schema, host, path (and also indirectly port) into one single field.