Merge pull request #1761 from TheBlueMatt/2022-10-user-idempotency-token

Provide `send_payment` idempotency guarantees

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

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

diff --cc lightning-invoice/src/utils.rs
Simple merge

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

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

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

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