Fix bc-worker build

[Traf333]

Context

this PR fixes missing usage of type

   --> src/rpc/worker_api_direct.rs:346:46
    |
346 | ...                   return match GLOBAL_SCHEDULED_ENCLAVE.update(bn, enclave_to_set) {
    |                                                             ^^^^^^ method not found in `GLOBAL_SCHEDULED_ENCLAVE`
    |
    = help: items from traits can only be used if the trait is in scope
help: the following trait is implemented but not in scope; perhaps add a `use` for it:
    |
18  | use lc_scheduled_enclave::ScheduledEnclaveUpdater;

was broken by this PR

[kziemianek]

Thanks, I've added feature checks in linked PR.