Merge pull request #3107 from mhrheaume/mhr/closure_reason_abandoned

Updated `ClosureReason::HolderForceClosed` with whether txn was broadcasted.

diff --cc lightning/src/chain/channelmonitor.rs
Simple merge

diff --cc lightning/src/events/mod.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/shutdown_tests.rs
Simple merge