Function fileServersFromEvent

fileServersFromEvent(event: NostrEvent | undefined): readonly string[]
The servers a file-server list names, in its order, as root URLs.
Parameters
- event: NostrEvent | undefined
  A kind 10063 list, or nothing.
Returns readonly string[]
Server URLs, deduplicated.
Example
```
fileServersFromEvent(list); // ['https://blossom.primal.net/']
```