drum: add %file-server to boot priority
File server needs to be started with priority in order to ensure the
view apps can poke it, regardless of set ordering.
%metadata-store
==
:: ensure chat-cli can sub to invites
- (sy ~[%chat-hook])
+ :: and file server can receive pokes
+ (sy ~[%chat-hook %file-server])
==
++ sort-by-priorities
=/ priorities priorities
