Merge pull request #2128 from valentinewallace/2023-03-route-blinding-groundwork

Route blinding groundwork

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

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

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

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

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