Merge pull request #949 from TheBlueMatt/2021-06-send-priv-update

Send channel_update messages to direct peers on private channels

diff --cc fuzz/src/chanmon_consistency.rs
Simple merge

diff --cc lightning-background-processor/src/lib.rs
Simple merge

diff --cc lightning/src/ln/channelmanager.rs
Simple merge

diff --cc lightning/src/ln/functional_test_utils.rs
Simple merge

diff --cc lightning/src/ln/functional_tests.rs
Simple merge