Merge pull request #2810 from TheBlueMatt/2023-12-arbitrary-fuzz-config

Update `full_stack_target` to take an arbitrary config object

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

diff --cc lightning/src/ln/channel.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

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

diff --cc lightning/src/onion_message/messenger.rs
Simple merge

diff --cc lightning/src/routing/gossip.rs
Simple merge

diff --cc lightning/src/routing/router.rs
Simple merge

diff --cc lightning/src/util/test_utils.rs
Simple merge