Add `HTLCDescriptor::witness_weight` #84

Job	Run time
benchmark	20m 10s
build-tx-sync (ubuntu-latest, stable)	4m 31s
build-tx-sync (ubuntu-latest, beta)	4m 16s
check_commits	1h 18m 37s
check_release	2m 3s
build-tx-sync (ubuntu-latest, 1.75.0)	4m 48s
build (ubuntu-latest, stable)	44m 1s
build-tx-sync (macos-latest, stable)	5m 5s
build (ubuntu-latest, beta)	46m 30s
coverage	8m 13s
build-tx-sync (macos-latest, beta)	4m 26s
build (ubuntu-latest, 1.63.0)	59m 4s
build-tx-sync (macos-latest, 1.75.0)	5m 13s
fuzz	1h 29m 50s
build (windows-latest, stable)	1h 21m 0s
incremental-mutants	6h 0m 14s
build (windows-latest, beta)	1h 19m 55s
build (macos-latest, stable)	42m 49s
linting	1m 2s
rustfmt	14s
build (macos-latest, beta)	41m 38s
build (macos-latest, 1.63.0)	49m 9s
	17h 12m 48s

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