Function recover_scan_idxes_for_activity

pub(crate) async fn recover_scan_idxes_for_activity<F, FF, T>(
    scan_from_idx: TweakIdx,
    used_tweak_idxes: &BTreeSet<TweakIdx>,
    check_addr_history: F,
) -> Result<RecoverScanOutcome>
where
    F: Fn(TweakIdx) -> FF,
    FF: Future<Output = Result<Vec<T>>>,

A part of WalletClientInit::recover extracted out to be easy to test, as a side-effect free.