Add pending `SpliceDetails` to `ChannelDetails` #23537

Job	Run time
benchmark	18m 22s
check_docs	5m 3s
check_release	3m 3s
ext-test	7m 37s
build-cfg-flags / build (self-hosted, 1.75.0)	13m 34s
linting	2m 28s
fuzz	1h 27m 55s
build-features / build (self-hosted, 1.75.0)	28m 30s
rustfmt	15s
build-bindings / build (self-hosted, 1.75.0)	29m 44s
build-nostd / build (self-hosted, 1.75.0)	13m 24s
build-workspace / build (self-hosted, 1.75.0)	20m 36s
fuzz_sanity	18m 2s
build-sync / build (self-hosted, 1.75.0)	30m 7s
tor-connect	7m 32s
coverage	57m 44s
notify-failure	-2s
	5h 43m 54s

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