Introduce `FundingTransactionReadyForSignatures` event #19799

Job	Run time
check_release	2m 21s
build-tx-sync (ubuntu-latest, beta)	4m 31s
build-tx-sync (ubuntu-latest, stable)	4m 39s
linting	2m 28s
build-tx-sync (macos-latest, 1.75.0)	9m 6s
build-tx-sync (ubuntu-latest, 1.75.0)	4m 54s
build (self-hosted, beta)	1h 19m 49s
build-tx-sync (macos-latest, stable)	4m 52s
build-tx-sync (macos-latest, beta)	4m 19s
build (self-hosted, 1.63.0)	6h 0m 19s
build (self-hosted, stable)	1h 19m 3s
build (windows-latest, stable)	2h 18m 5s
rustfmt	14s
build (macos-latest, stable)	1h 12m 14s
build (macos-latest, 1.63.0)	1h 30m 31s
ext-test	6m 2s
fuzz	53m 31s
benchmark	17m 9s
coverage	13s
	15h 34m 20s

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